Using sketchbook

Sal uses sketchbook.  I downloaded this.  But my question is how does Sal get the screen on sketchbook have a coordinate grid and have the black screen?  I want to be able to use this with my online classes this next term.  I teach at the high school and college and would like to have a similar set up as Sal.  Maybe Sal could create a tutorial on how to get this set up?

Thanks for all you do.  I have been using Khan since 2008 and LOVE what you do!  Truly inspiring!  Thanks so much for all the support you give students, teachers and parents.

Bob