In a way, it is best to work on documentation when you don't yet fully understand, because if you fully understand you yourself don't need the documentation any more :).

Obviously you don't want to write documentation that is incorrect or doesn't make sense, but the code-review process should prevent that from being published.  Plus, if you are going to work on documenting something, you can always ask for help either on this mailing list, or on the IRC channel (#twisted or #twisted-dev on Freenode depending on whether your questions are about help with Twisted or help with contributing to Twisted itself).

Glad I could point you in the right direction, and hope to hear more from you in the future,

-glyph