First, make sure that you purchased washable ribbon, and not floral ribbon. It probably is synthetic, so don't use a cotton setting on your iron. Press in half, so now it's 1" wide. Working from the back of your quilt, open the ribbon and match the fold with the raw edge of the quilt. Pin in place and stitch close to the edge. After you have stitched all the way around, turn the quilt over, fold the ribbon down and pin. Stitch close to the edge. In theory, you could just fold it over the raw edge, pin and stitch from the front, but doing it from the back first will give you a better result and won't take that much longer.
You will need to miter the corners and join the 2 ends. here's a link to binding tutorials on this site:
http://www.quiltingboard.com/search....inding&u=&s=10