If I'm hearing the question correctly, the answer is:
1) Near the top right corner of every page on the forum (just under Search) there are four links. Choose the leftmost one, titled "User Control Panel".
2) On the resulting page, choose "Profile" from the list of choices on the left.
3) Click "Edit signature" from the new choices under "Profile".
You can then paste in text (up to 9999 characters, but realistically keep it to a couple lines), links, and image references.
Links are entered as
Images are entered as
If you want a ready-made Uni/IVY signature like mine, you can visit the University Killboard
, "Search" for yourself (top bar, third from the right), and click "Extended Signature" at the bottom of the "Menu" box on the right. This will provide a few options you can copy/paste from.