To call it up, click on the small notebook located to the right of your WGT nation flag at the top left of your game screen.
Keep in mind that besides being able to use it in single play only,
You cannot scroll through the book.
If you pick a practice hole using the "WGT Community" "Golf Courses" route the notebook only opens and stays at hole #1 of the course you select. It will not open to the hole you are actually playing.
Notes do not carry over from one course to another. For example, notes entered for St. Andrews #18 on that course will not show when you play St. Andrews #18 as part of the Best of Famous Holes.
In CTTH you must enter your notes BEFORE you hit the shot. After you hit it the game automatically moves on to the next hole and you cannot access the notebook to enter notes on the shot you just hit.
The same applies to any shot that is holed in stroke play. Once the ball goes in the hole you can no longer enter notes for that hole.
I'm still waiting for a refund WGT offered on the notebook I bought.