First, you wanna go to http://www.xat.com/web_gear/chat.php#top
Second, you will see some pictures on the left. Click one of them to pick your style. When you do, you'll get a preview of it on the right.
Third, after you picked your style, scroll all the way down and look to your left. There should be a code. Copy it.
Fourth, On your forums, create a catagory called chat and a board called forums chat. Paste the code in the description.
Fifth, after you save it, tell your friends about it and have fun chatting!

This guide was made by Blind.