If you have Chessmaster 10th Edition, then you should read the User's Manual... it contains step-by-step instructions for playing online.
Some caveats:
You don't need to create a new account... just use the one you're using to access the forums.
You'll need to install all the patches in order to play online (you'll get an error if you don't). You can find them in the Chessmaster 10th Edition Downloads.
