What can I add to the canvas? Can I add my own documents? Can I add my own lessons?

You can certainly upload your own material to the canvas, the whiteboard that’s connected to each lesson.  The canvas supports both YouTube links and image files. The best way to upload documents (such as powerpoint, word, PFD, CD Rom or printed files) is to take screenshots/pictures which you put right onto the canvas. That way you and your students can interact with the material using the canvas tools (e.g. drawing/typing over the image files to give them two way interactive powers!).  To see exactly how to do it, check out this video.