you need to go to a site like tickerfactory, mickeypath, magicalkingdoms.com etc.... then go through the steps of creating your ticker. once you've picked a background, a slider, and the writing, it'll give you a load of technical jargon that you need to copy.
once you've copied the jargon, click on user cp at the top left of the boards, then on the left it says edit signature. paste the technical jargon bit into the box and hit save.
that should work
there's normally a couple of different codes, on magicalkingdoms.com (i use that one), you need to pick the one that says "BBCode or UBBCode™ (vBulletin, IPBoard, etc) Used on most message boards"