So I used this site: http://www.domesticimperfection.com/2011/09/triple-book-slings/. Again, let me say, I am NOT a sewer! I think I've hemmed some pants and shortened curtains before. That's it. So, if I can do this, so can you! Albeit I might have had to make some adjustments. I should have measured them and then chosen the size of slings I wanted. But no, I had to do things the hard way. I did the large size first, had it all done, and went to put Caden's books in and you couldn't see any of them! So, back to the sewing machine. I ripped out the seam, made a cut, and sewed it back up.
I bought some curtain rods, shown in the picture below, which are clearly not going to cut it. I couldn't find any wooden dowels longer than 3 feet though. My slings are 4 feet long. Again, had I thought this through more, I would have cut my fabric shorter to use the cheaper wooden dowels. I would shorten them now, but I already put holes in the wall. Not a fan of making more holes than necessary! I will be going back to the store to get a sturdier rod to hang the book sling with.
I was very happy with my $9 double curtain rod hangers. They are wooden and brown and match Caden's room perfectly. They are quite sturdy, too. Overall, for two book slings (the other one is awaiting the shortening process) I spent about $35. I love that it saves space and isn't so bulky like a bookshelf.
I hope you other non-sewers out there find this helpful! Maybe you won't make the same mistakes I did!