The Past perfect is for actions completed before other actions in the past. Past perfect highlights the sequence of events in the past.

It is formed with the auxiliary verb “had” + the past participle.

Examples:
I went to the party after I had left my date at the restaurant.
My parents had already seen the world by the time I was born.
If you had tried to kiss me that first night, I would not have gone out with you agin. .
Until you met me, you had not believed in love at first sight.
I had never seen such a tall human, before I went to the Knicks basketball game.
They weren’t hungry because they had eaten before they got to our house.

Past perfect continuous is formed with the auxiliary “had” + been + the present participle
(-ing form of the verb)

Examples:
He had been trying to change his life when the police arrested him.
She had been auditioning for a different reality show when they admitted her to the Amici TV program.