1) Go to your profile (there's a button on the upper left hand of each of your posts that gets you there quickly.)

2) Click on "User CP" button. I think it's the second from the left, or close to there.

3) Click on "Edit Profile" Again this is roughly two or three from the left in the row.

4) Scroll down till you get to your Signature block. I think it's about the fourth or fifth from the top.

5) Edit as you wish.

Hope this helps. Some of the data changes depending on how often you post, so the exact area may differ, but this should be close!

Good luck!!!