If you are interested in development, you should have a basic knowledge of Python.
You can find the official documentation of Python in the official Python website
If you’re going to code the GUI, you need knowledge in GTK+ or Qt4; see GTK+ Website and Qt Website
However, we do have some tasks that don’t require coding ability and welcome your help: see on HowToContribute.
Emesene rocks! :D (ok, this now is to stay happy in this page! >:) )