There, that should do it; I must say I didn't expect signatures to be unavailable by default. Makes me want to go back and see what else I've missed. These forums are incredibly customizable, more so than many others I've worked with.
Anyway, I've globally enabled sigs, so any posts you make from now on should contain your personal sig. A good choice of art by the way; definitely fits your character.
P.S.: In case you hadn't noticed it, I've enabled you as a moderator, so you'll be able to perform some advanced tasks in case I'm unavailable.