Leave Your Mark!
Y'all can probably figure this all out for yourselves, but in the event that you're like me (who had no clue at first what in the world this was), then here are some quickie instructions!
Below the wood-paneling stuff, you can see that there are three colored blocks: red, blue, and green. Click on the color you want, and then click again somewhere on the paneling. A block in the color you chose will show up. Now you can write stuff! (ooo...ahhh...)
To save your artwork, go down to the little menu thing that's below the colored blocks (the default setting is "Save", so just push the "Do" button)...you can also clear the board or reload it. Anyway, have fun!