>>308
You can't just learn that from one day to the other.
There are some rules of thumb for the indicative. The subjunctive is a lot messier because English can't into subjunctive (i.e. it has no conjugations, so you have to look for certain cues).
Do note that tenses won't match all the time, and that one tense may translate to another depending on the context.
Also, for some god-forsaken reason, some tenses have several names (e.g. potencial simple -> condicional simple, pretérito indefinido -> pretérito perfecto simple)
Remember these are just rules of thumb.
indicative mood:
presente -> present simple
pretérito perfecto simple -> past simple
pretérito imperfecto -> past simple
estar(pret imperf.) + gerundio -> past continuous
pretérito perfecto compuesto -> present perfect (they're similar for the most part)
haber(presente) + estado + gerundio -> present perfect continuous
pretérito pluscuamperfecto -> past perfect
futuro imperfecto simple -> future simple (will)
ir(presente) + a + infinitive -> going to + verb / future simple (will) / present continuous(future) (the choice between the first two is mostly region dependent, though there are some marked differences if you bother to read on them. I threw the last one in because it exists)
future perfecto compuesto -> future perfect / going to + have + participle (not sure about the last one, but I'm including it just in case)
condicional simple -> would + verb / could + verb / might/may + verb (examine the context)
condicional compuesto -> would + have + participle / could + have + participle / may/might + participle (conext is your friend)
pretérito anterior has dropped so drastically in use that it's no longer taught. Hell, I don't even know how to use it. There are remnants of it in literature.
subjunctive:
More often than not, subjunctive tenses are preceded by 'que'
present:
1. I need/want you to say/do/bring… -> necesito/necesito que digas/hagas/traigas…
2. I hope/expect that you say… -> espero que digas…
3. I recommend/request/demand that you do… -> Le recomiendo/solicito/exijo que haga…
pretérito imperfecto
Often used with the second conditional:
If I had something to say, I would say… -> si tuviera/tuviese algo que decir, diría…
pretérito perfecto
Hard to find cases, but…
I hope (that) your gathering has been a success -> Espero que tu reunión haya sido exitosa
pretérito pluscuamperfecto
Often used for 3rd conditional:
If I had known, I would be elsewhere -> Si hubiera sabido, estaría en otro lado
futuro imperfecto
Used mostly min legalese. I'd say it serves the same role as the present subjunctive sans giving encouragement:
El que llegue a la meta primero recibirá un premio -> The first one to reach the goal shall receive a prize
El que llegare a la meta primero recibirá un premio -> The one who were to reach the goal first shall receive a prize
I don't know whether English has an actual equivalent to this tense or its perfect counterpart, so I just came up with a sentence that conveys a similar meaning
I believe those sentences is gramatically correct. Feel free to correct them
futuro perfecto
Just like the futuro imperfecto, its use abounds in legalese:
Those who were to have arrived late shall be sanctioned with a fine -> Aquellos que hubieren llegado tarde, serán sancionados con una multa
I think that just about covers everything. If I missed one, post about it.