Welcome to XMonad.  Tutorials abound online, but here is what you need to 
get started:

First, if you haven't already, you need to log out of your current X session,
and set your session to "xmonad" by clicking "session" at the bottom of
your login screen.  

General Commands:

Alt-Shift-Enter - Open a new terminal
Alt-Shift-r     - Run a command (bar at the bottom of the screen)
Alt-Shift-s     - Run SSH with completion (bar at the bottom of the screen)
Alt-Shift-c     - Close the current window
Alt-Shift-l     - Lock the screen
Alt-Shift-q     - Quit the X session

Window and Screen Specific Commands:

Alt-spacebar     - Change the window layout on the current screen
Alt-enter        - Make the currently highlighted window the primary/master window
Alt-j|Alt-h      - Jump to the left physical screen
Alt-k|Alt-t      - Jump to the right physical screen
Alt-i|Alt-c      - Rotate the window focus clockwise
Alt-u|Alt-g      - Rotate the window focus counterclockwise
Alt-[0-9]        - Switch desktop n into the current screen
Alt-Shift-[0-9]  - Move the currently highlighted window to desktop n
Alt + mouse move - Untile a window (make it floating)
Alt-Shift-t      - Retile a floating window