On seperate computers, log in to your respective profiles.
Go to the WGT Community link and search for your brother's screen name. Once you find him go to his profile page and select the "Add as Friend" link.
Once he accepts he will appear on your profile page friend's list.
Now select the "play" link and a new window opens. Choose "Create a Group". Set up your game and select "Create Group" at the bottom of the screen.
You are given several options for opponents. Choose the "Friend" button. Choose your brother's screen name off the list. An invite will be sent. when he accepts you can select "Tee Off".
Hope this helps, good luck.