how to use ce dont

Bonjour Kathryn, Ce dont is an indefinite relative pronoun. It's used for the same reasons as dont (e.g., when replacing something that begins with de) but when there is no antecendent. Compare: Voici le stylo dont tu as besoin - Here's the pen you need. Je ne sais pas ce dont j'ai besoin - I don't know what I need.

Un grand merci, Laura.