You make the past perfect by saying "had + past participle".
1. After Yara had finished her work, she went to lunch.
(First she finished her work and then she went to eat lunch.)
2. I washed the floor when the painter had gone.
(First the painter left and then I washed the floor.)
3. Harold had known about it for a while.
(First he knew about it, then others knew about it)