When do I use perfect tenses when speaking Spanish?

Question

Also, how do I conjugate normal and perfect past tense?

Answer 1

Not very often is one answer. Perfect tense is used when you have an event (or events) in the past with effects into the present.

He visto a mucha gente trabajando - I have seen many people working. It happened, it may still be happening, we don't know from the sentence.

This tense is not used very much in Spanish, but really it's not used that much in English either. Don't make the mistake of using it for a simple past event (use the preterite) or an ongoing activity in the past (use the imperfact).

The tense is very easy: the present tense of the verb haber plus the perfect passive participle (PPP). The PPP sounds complicated, but is really very simple: just strip off the ending of the verb and add either "ado" or "ido" (for "ar" verbs or "er/ir" verbs). Venido < venir, Tenido < tener, Hablado < hablar, etc. So, putting the two together (with all the conjugated forms of haber):

He venido - I have come
Has tenido - You have had
Ha tocado - He has touched
Hemos perdido - We have lost
Han comido - They have eaten

There are a bunch of irregular participles too, but they're pretty simple: hecho = PPP of hacer, dicho < decir, roto < romper, etc.