A reference link on Youtube on how to make book cover.
http://www.youtube.com/watch?v=-pGO0gsZP-A
I didn't make it in this way though. I sew the 2 fabrics together(sew the elastic band and lace inside at the same time. And in advance I'd iron a backing sheet to make the fabric harder. I like check patterns as you see... The squares also serve as a ruler for me to keep the sewing line straight) and leave one side opened. Then I flip it inside-out and close the open edge. Well.. it's difficult to explain in words. Hope you get what I mean.