Click Control Panel and then New Message. Type in his name as the recipient and then your subject line and the text of the msg and you are golden.
or you could just find one of his posts and click his name and then click "send PM" on the drop down menu.
Or, you can push: Up, Up, Down, Down, Left, Right, Left, Right, B, A, B, A, Select, Start... (If you do not get this joke, you might be old!)