I've done a lot of these and they are really very easy. Do you know the basics of making book covers? i.e. cutting (cardboard or whatever you're using), outer covering and inner covering......
Well, you cut the /cardboard/ to the size you want your book to be. Then out of something a little thinner (but as strong) than what you used for the cover, cut another strip 3/4 to 1 inch wide and the height of your book. Since I like to have the posts that holds the book together covered, I add another piece about 1/2 to 3/4 inches wide. These widths are just "for instance" can be whatever looks good to you and/or the style of your book. You don't have to add the extra strip, I just think it's a nicer finish. Line up and make holes for the posts in the wider strips.
Lay out the outer covering good side down. Lay the /cardboard/ cover and strips out side by side and adhere them to the outer covering by whatever means you are using--glue, iron on adhesive, sewing.....I use a couple of bamboo skewers to space the stripes about 1/8 inch apart, but do a test to see if this is going to be enough room to allow them to fold over. Adhere the inner covering and bind the holes for the posts.
Paper is cut, the holes punched to line up with what you put on the strips and stacked and the covers positioned over it all. Put in the post screws, close the inner strip, close the book.
I'm not too good at illustrating, but I've made a stab at it. Hope it helps some. Good luck with your project!
Oh, didn't illustrate, but if you want the "spine" bound, make a strip of thin card the height of the book and cover with the cover material. Make it wide enough to enclose depth of the page stack and come over past the post screw holes. Line up and make holes for the post and position this strip in place before you put on the covers.
Shylaah