It's a little complicated, but here's how to do it:
[url=http://www.yourlink.com]Your Link[/url]
1. Click on 'Select' and then copy the code.
2. Go to your forum profile and paste the code into your signature.
3. Replace http://www.yourlink.com with the full address of the site you want people to visit when they click on the link. Make sure that you don't erase the = before the address or the ] after the address, or the link may not work.
4. Replace the part that says Your Link with whatever text you want people to see. Be careful not to erase the brackets on either side of it.
5. If you'd like, add another link by pasting the code again and following steps three and four.
6. Save your profile.
7. Go to one of your posts and test the link.