What does it mean when it suggests adding artworks or stories? I am not very good at drawing or writing tales.

Basically, this is about all the stories in that you have experienced involving magic or magical stories, that you feel are important enough to go into your BoS. As for the artworks, if you were to do a magical sketch or drawing/art that you created or were given involving magic or even pictures of magical things that you believe are appropriate to be in your BoS (Wicca/Magick). Those would be the kind of things to put in your BoS. The most important thing is to have fun with your learning so there is no need to be expert at either drawing or writing.