Hey! I see you've added me as a friend ^-^ *gives candy*
Hehe, I'm 12 too~
And about how to edit your profile:
From your normal forums webpage, scroll up until you see the black bar with your member name on it. Click on that. You should now see a range of options such as 'My Profile' and 'My Content' et cetera. Click on the option that says 'My Settings' It's pretty straightforward from there. Click on 'Change my photo' if you want to change your avatar, click on 'Edit my About Me Page' if you want to edit your about-me page et cetera.
That's about it. Also, if you want to change your signature, follow steps 1 and 2 and then:
To your left, you should see a list of options. Click on the option that says 'Signature' Change your signature from there!
Anything else you want to know? ^-^