Help with posting Signatures/Thickers

I don't know what I'm doing wrong...lol...but I can't seem to find where I can have like some of you with a detail info as a signature with each posting.  I want to write Start Weight: Lost: Goal: After Surgery, etc but I'm really stuck and don't get why I can't finding, I've done this before but on this site, can't...lol

TIA everyone & Amazing job to everyone, you all are inspiring!!
Nathalie_Can