For those who may not know this already, the forum signature is that little area of text and/or picture

that appears under a person's message board post. Putting your personal link in your forum signature

is a good idea, and it takes you less than a minute to do it.

You need to use BBCode. BBCode is what will make your signature appear exactly how you want it, for example:
If your username is testdrive your personal url is http://person.al/testdrive

Your signature forum code it will be:
[url=http://person.al/testdrive]  Text you want to be clickable [/url]

"Text you want to be clickable" is your personal information, for example:
[url=http://person.al/testdrive] Obama Online Profile [/url]

Note: Replace the blue link above with your personal profile link, and "Text you want to be clickable"  with your personal info ,

and your have your own signature.