Measure your bookcase. Get the measurements for both length and width.
Buy a curtain rod and brackets. A lighter rod is better. Also make sure the curtain rod is long enough to stretch from one end of the bookcase to the other.
Get curtains for the bookcase. Look for curtains that match the decorating style of the room. Make sure the curtains are both long enough and wide enough to cover the bookcase. If they are not wide enough, buy more than one set of curtains.
Hang the rod brackets on the bookcase using screws. Drill holes in the bookcase's moulding with a drill. Choose long screws -- at least 2 inches long.
Slide the curtain over the curtain rod. If you've bought a curtain set that requires curtain hooks or clips, attach the clips to the curtain before sliding the curtain onto the rod.
Hang the curtain rod up on the curtain brackets.
Screw in hooks for the curtain tiebacks. Place these so that they're about halfway down the bookcase.
Attach the tiebacks to the hooks; there should be a small hole on each end of the tieback that will allow you to do this.