Hi Steven, I'll give it a shot.
The pronoun "ce" is used whenever the following relative pronoun (qui or que) refers to an idea that is not specifically mentioned in the same sentence. For example:
Natalie a un livre qui parle de Napoléon. -- Natalie has a book which talk about Napoleon.
Dans ce livre, elle trouve ce qui l'intéresse. -- In that book she finds what interests her.
Elle y apprend ce que Napoléon a fait. -- She learns from it, what Napoleon did.
The first sentence uses "qui" as a relative pronoun which refers to "un livre".
The second sentence uses "ce qui", which refers to a general idea of what interests her. There is no clear target in the sentence to which a mere "qui" could refer. It is "ce qui" because that is the subject of the sentence.
The third sentence uses "ce que" because, again, it referes to a general idea, namely that which Napoleon did. Also, it is the direct object ot the sentence, hence "ce que" instead of "ce qui".
As a rough guideline you can use "ce qui/ce que" whenever you would use "what" in English. If you can use "which", itis "qui/que".
-- Chris (not a native speaker).
