If it is a hard handle you need to make straps to attach to the ends to hold it on or attach "D" rings to the bag for the handle to attach to. A fabric handle can be attached to the ends and hidden in a seam.
Cut four 3 1/2 inch strips out of leather about an 1 1/2 inches thick. Take two strips and sew them together.Glue to the purse, sew in place with handle.