A Step-By-Step Guide to Making Links in your Signature on Yu-Gi-OhRealms
Liger's Trading Site
The Idiot List
Photo Album
Photo Album 2
How to make Links

OK, the first thing you need is the web address to the thread you want to link to.  For example, if you want to put a link to your ref list, you need to get the web address to that thread.  So, find that thread in the Good Traders Forum or the Trading Forum, or wherever it is, and copy the web address to your computer's clipboard.
Now, you need to go to "User CP" in the menu bar that's integrated into the Yu-Gi-OhRealms logo at the top of the page.  There is a gray, horizontal menu bar with different options in the User Control Panel.  Select "Edit Profile", which is the second choice from the left.  Scroll down to where it says "Signature" in bold on the left, and a large text box on the right.  This text box is where you will enter codes to link your thread.
Click in the text box and type this:
Now paste your link from your computer's clipboard:
Now add a square bracket:
Give your new link a title.  This will appear on all your posts, so make it short and descriptive:
[url=http://www.yugiohrealms.com/forum/blahblahblah]my refs
Now close it up with the final code:
[url=http://www.yugiohrealms.com/forum/blahblahblah]my refs[/url]
You have to make sure there are no extra spaces and no extra characters, or the link won't work.  The only place you can put spaces and other stuff is in the name of the link.
Click the "Submit Modifications" button at the bottom to save your work, and you're all done.  Simple, right?