With simple tenses, the tense is past, present, or future. With progressive tenses, the tense is ongoing during a time in the past, present, or future. The perfect tense is a weird tense in the English language--although other languages certainly have comparable tenses.
With perfect, the verb is relative to something that happened before. Look at present perfect (this is from Azar's Understanding and Using English Grammar, 4th Edition):
This excerpt from Azar is intended for ESOL speakers. Present perfect is natural for native speakers, but when we start to dissect it, it's suddenly confusing. I believe this is because we don't normally consider the time association with perfect tense.
Past perfect is essentially the same, but the event and the reference point are in the past:
When I moved to Mexico, I had studied Spanish for three years.
I had known Dan for ten years before I met his sister.Future, again, works the same way.
When I graduate next year, I will have gone to school for ten years.The uses of perfect do not stop with time. As writers, the better we understand the verbal tools we have, the better we use our language.