I know I'm not an admin or anything, so I hope you don't mind me answering your question.
Up near the top on the page, click User CP. (It's on the orange bar near the top). Then under Settings & Options click Edit Signature.
Hope this helps!
3A, medium fine. Currently avoiding shampoos, 'cones, 'xanes and sulfates. Hair length - a bit beyond BSL. Mostly CG since July 2, 2008.