How to make a quest to destroy the entire enemy base?

[tomoraider]

Hi, I'm sort of new to the World Editor, and I have a question
I made a map where I want to make a quest I have to destroy entire enemy base. I know how to make a quest to destroy one building or kill somebody, but I don't know how to make a quest to destroy the entire base
Also, I want to make second quest which I get when i finish the first one and I also don't know how to do that
Thanks for help