How do you express the past perfect tense?
please explain me about the usage of "past perfect tense" With the simple past tense!

Question

Answer

You use past perfect to describe the situation behind (or the situation which causes) the past simple event. The extra bonus is that you can put past perfect before or after past simple, and the chronological order stays the same.

Have a look online for "past perfect past simple" and you'll get plenty of examples.