There's more than one way to bind a book. Start with Saddle Stitching. You see saddle stitching every time you pick-up a magazine. Two staples on the spine of the magazine. That's a Saddle Stitch.
Saddle Stitching is relatively inexpensive. The catch: if there are too many pages your book doesn't lay flat.
So, if you have more than 20 pages to bind, Coil Binding, Wire-O Binding, or Comb Binding can be better solutions. These options can cost a little more, but they're very professional looking... and your books lie flat.
The diagrams below provide a visual illustration of various binding options.