Regular verbs follow the pattern for the endings, but irregular verbs are different. They may take a different ending, or look different all together. In English, for example, "to go" is an irregular verb. I can say "I go" but when I use it in the past it's "I went," so "go" becomes "went" a completely different looking word.

The irregular verbs in the present are on the first page of your review packet. They include verbs like: poner, estar, ir, ser, querer, poder, poner, etc.

Here is an example:

Estar
Estoy Estamos
Estás Estáis
Está Están

When we conjugate (change the verbs into the 6 different people) we take off the ending and add a new ending, but there are some verbs that also change in their root or base. These are called shoe or stem-changing verbs.

Dormir (to sleep), for example, changes from "o" to "ue" when you conjugate it. All forms change except for "nosotros" and "vosotros":

Yo duermo Nosotros dormimos
Tú duermes Vosotros dormís
Él duerme Ellos duermen

The present progressive or "ing" like in "I'm writing" is formed in Spanish with the verb "estar (to be)" and with the ending "ando" for verbs that end in "ar" (like "hablar") and "iendo" for verbs that end in "er/ir" (like "comer" and "vivir").

For example:
I am talking.= Estoy hablando (I conjugated "estar" in "yo" form, and I took off the "ar" and added "ando" to the verb.)

She is swimming.=Está nadando.

Conjugation:
To conjugate means to change a verb (an action) into the different people and tenses. For example:
I eat, you eat, he eats, we eat, you all eat, they eat.

You need endings in Spanish to conjugate. Every verb in Spanish in its original form ends in Ar, Er, or Ir. For example: hablar (to talk), comer (to eat), vivir (to live).
All the verbs that end in Ar (like hablar, nadar, pasar, etc.) have the endings: o, as, a, amos, ais, an.
Every ending corresponds to a person or persons. Before you can add the ending you must take off the "ar." For example: "hablar" goes to "habl" and then to "hablo"

o=yo (I) Hablo (I speak)
as=tú (you) hablas (you speak)
a=él/ella/usted (he, she, it, you formal) habla (he speaks)
amos=nosotros (we) hablamos (we speak)
áis=vosotros (you all) habláis (you all speak)
an=ellos/ustedes (they, you all) hablan (they speak)

Verbs that end in Er (like comer/to eat) have these endings:
o=yo Como (I eat)
es=tú Comes (you eat)
e=él/ella/usted Come (he eats)
emos=nosotros Comemos (we eat)
éis=vosotros Coméis (you all eat)
en=ellos/ustedes Comen (they eat)

Verbs that end in Ir (like escribir/to write) have these endings:
o=yo Escribo (I write)
es=tú Escribes (you write)
e=él/ella/usted Escribe (he writes)
imos=nosotros
ís=vosotros
en=ellos/ustedes

The imperfect is a form of the past tense. We use it when:
- We talk about things that happened an indefinite amount of times (if I know the number of times it's preterit and not imperfect) (When I was (era) little...)
-We talk about things that were happening at the same time (I was talking (hablaba) on the phone when he came in)
-Any time I use "ing" in the past (I was walking (caminaba) to your house when...)
-Any time I want to say "used to" (I used to go (iba) to summer camp every summer)
-Any time we talk about a habit (I washed (lavaba) my car every Sunday)
-Any mental and emotional actions such as wanted, loved, needed, felt, etc.
-For weather, time, date, and age (When I was 9/cuando tenía 9 años. Or It was January 15/Era el 15 de Enero)

Formation:
Endings for Ar: aba, abas, aba, ábamos, abais, aban
Endings for Er/ir: ía, ías, ía, íamos, íais, ían

Hablar: hablaba, hablabas, hablaba, hablábamos, hablabais, hablaban
Comer: comía, comías, comía, comíamos, comíais, comían

Irregulars: (there are only 3!)
Ser: era, eras, era, éramos, erais, eran
Ir: iba, ibas, iba, íbamos, ibais, iban
Ver: veía, veías, veía, veíamos, veíais, veían

Reflexive means that you do the action to yourself, like in taking a shower: bañarse, or to shave: afeitarse.
You conjugate them by the ending ar, er, or ir like normal, but you must take off the "se" and add a pronoun (because of the "se") like me (for I), te (for you), se (for he or she), nos (for we), os (for vosotros/you all), se (for they, or ustedes/you all)
For example: bañarse: to take a shower

In the present:

Yo me baño (I take a shower)
Tú te bañas (you take a shower)
Él se baña
Nosotros nos bañamos
Vosotros os bañáis
Ellos se bañan

In the preterit:

Yo me bañé
Tú te bañaster
Él se bañó
Nosotros nos bañamos
Vosotros os bañasteis
Ellos se bañaron

**You don't use the reflexive pronouns (me, te, se, nos, os, se) if you do the action to some one or something else. For example:
Yo me baño (it's reflexive because I do it to myself)
Él se baña (it's reflexive because he does it to himself)
Yo baño a mi perro (it's not reflexive because I bathe my dog, not myself)

The preterit is a verbal tense used to talk about the past. It has its own endings:
For verbs that end in "ar" like hablar: é (yo), aste (tú), ó (él/ella/usted), amos (nosotros), asteis (vosotros), aron (ellos/ellas/ustedes)
hablé hablamos
hablaste hablásteis
habló hablaron
For verbs that end in "er/ir" like escribir: í (yo), iste (tú), ió (él/ella/usted), imos (nosotros), ísteis (vosotros), ieron (ellos/ellas/ustedes)
escribí escribimos
escribiste escribísteis
escribió escribieron

There are many irregular verbs, but the majority of them take these endings: e, iste, o, imos, isteis, ieron (no accents on any of them)
estuve estuvimos
estuviste estuvisteis
estuvo estuvieron

The highly irregular verbs (they don't follow any pattern and you must memorize them) are:
Ser: fui, fuiste, fue, fuimos, fuisteis, fueron
Ir: fui, fuiste, fue, fuimos, fuisteis, fueron
Decir: dije, dijiste, dijo, dijimos, dijisteis, dijeron
Traer: traje, trajiste, trajo, trajimos, trajisteis, trajeron
Dar: di, diste, dio, dimos, disteis, dieron
Ver: vi, viste, vio, vimos, visteis, vieron

The subjunctive is a mood. When a speaker or writer expresses their feelings about what they are saying/writing. For example: 1) I don't think my boyfriend loves me. Vs. 2) I know my boyfriend doesn't love me.
In sentence 1, we can see that the speaker expresses uncertainty about whether or not the boyfriend loves her. In sentence 2, the speaker is sure or certain that the boyfriend doesn't love her.
In English, the verbal tense (doesn't love me) doesn't change, but in Spanish, the tense in sentence 1 (the one with uncertainty), the tense chages from the present to the present subjunctive: No creo que mi novio me ame (not "que mi novio me ama"). However, the second sentence would not be subjunctive because the speaker is certain of what she is saying (Se que mi novio no me ama).

Simple tip:
When trying to decide whether to use ser or estar, ask:
Is is a place?
Is it a feeling or state of mind/health?
If it isn't, it should be ser. There are other rules, but if you ask those two questions you will get it right 90% of the time!!!!

Ser is used for characteristics (I am tall, I am nice), proffessions (I am a doctor), to say where you're from (I'm from Colombia).

Estar is used for places (I'm at school, or the party is at school), for mood or state of mind or health (I'm sick, I'm well, I'm sad), for the progressive (I am dancing, I am listening), for things that recently changed (the food is good today, or you are mean today)

The passive voice is used for:
mistery
legal documents
to leave the subject out of a sentence or to put the emphasis on the object

The rules are:
1. There is no subject or
2. If there is a subject, the emphasis is not on it, but on the object
3. The use of the reflexive (there is no subject, and it's conjugated in the third person)
4. The use of ser and/or haber
5. The use of the past participle

Examples:
1. The door was opened (La puerta fue abierta). We don't know who opened the door. There is no subject for the action to open.
2. I was hired in September. (Fui contratada en septiembre). We don't know who hired me. There is no subject.
3. Cars washed here. (Se lavan carros aqui) We don't know who is washing the cars. There is no subject.