If you click reply here to this note, you'll see the
http:// box at the top of the reply window. The box thingy is what's circled in red at the top of the screen shot. It's a button that says
http://
When you click it, you'll see the box pop up like the one the arrow is pointing to
Don't put your URL in that one, just type in whatever words you want everyone to see and click ok
Then, another box that looks the same will pop up. Just paste your URL in it and click ok.
Once you do that, you'll get the whole URL sequence in the reply box. Just highlight it, copy it, open another browser window and go to User CP, and just paste the whole code into your sig file.