first, past simple tense is used to talk about activities or situations that began and ended in the past. they are formed by adding-ed or it has irregular past forms, which you know espeashelly.
And past perfect expresses an activity that occured before another time in the past.
for example: I ate at noon. I was not hungry at 1:00 p.m. because I had already eaten before 1:00 p.m.
Activeity, wich happened very early. when I came home, my brother had wached on TV. he had already watched, before I came at home.
this is a difference between pastv simple and past perfect tense.. do you undersand?