Scalar Tutorials from other sites
Claremont Colleges has a nice set of video tutorials for using Scalar. That is another great resource for learning Scalar.
If you prefer a more text based option, Butler University has a another nice guide. They suggest using Scalar's open site for creating your book. That can be a great option if you want to have access to editing your book post-Denison.
You can host your images on your Google Drive, but that requires a bit more manipulation. You can see the information about how to get the correct URL for displaying your images on How to Embed Images from Google Drive to Your Website.