You don't have to be a programmer, designer, tester or technical writer to contribute to Ubuntu. You just have to be a knowledgeable user.
Have you seen AskUbuntu yet? If not, head over now, set up an account and you too can start helping follow Ubuntu users out. It's one of the many great things about Ubuntu that other distros simply don't have, although honestly, I wonder why other distros haven't set up a Stack Exchange site.
Outside of Ubuntu, Stack Exchange is a great ecosystem of sites full of helpful folks eager to answer your question!