Spanish tenses
I was never quite clear when to use the tenses in Spanish, especially the past tense.

I get the whole present tense, just dropping the -ar, -er, -ir and replacing them with the appropriate endings. But I am really confused with when to use the past tense.

So for preterite, I understand that it's for completed. It's the other past tenses that I'm really confused about. Is there only the preterite and imperfect because I feel like there's more. (he lavado, hablaba, etc.). Please correct me if I'm wrong and help me distinguish between them because this has puzzled me since the first time I learned Spanish.

Question

Spanish tenses
I was never quite clear when to use the tenses in Spanish, especially the past tense.

I get the whole present tense, just dropping the -ar, -er, -ir and replacing them with the appropriate endings. But I am really confused with when to use the past tense.

So for preterite, I understand that it's for completed. It's the other past tenses that I'm really confused about. Is there only the preterite and imperfect because I feel like there's more. (he lavado, hablaba, etc.). Please correct me if I'm wrong and help me distinguish between them because this has puzzled me since the first time I learned Spanish.

Answer

Most of the time you can think of the Spanish past as follows.
he/ha/han/hemos + ido/ado = have + verb. For example, he comido = I have eaten.
-aba and - ia endings = was + verb + ing; were + verb + ing; used to + verb.  For exaple, hablaba = we were eating or we used to eat.
preterite in Spanish = simple past in English.  Comí = I ate.

Answer

Past tenses in Spanish are actually quite complex.
Before choosing the tense, you need to take into account whether the action that started in the past 
- has finished or is still uncomplete:
Viajaron en ese tren vs viajaban en ese tren.
In the second case, they may still travel.
- when did the action happen.
If it was very recently, you may want to use "He visto a tu hermano" instead of "Vi a tu hermano". However, this difference applies in peninsular Spanish and can vary elsewhere, but it is a point to start seeing the differences.

Please check this site too:
http://spanish.about.com/od/verbtenses/a/two_past_tenses.htm

Answer

It is not easy to explain that even the Spaniards often used badly. THE PRACTICE is more than a formal rule
I washed, I've eaten. .. estabterminada say when the action
Washed, spoke ... is like simla action is interrupted or require an explanation.
It is complicated to explain and harder to explain writing