How to hem white denim shorts?

I recently bought a pair of white denim shorts online and I didn't realize that the bottom had no hem. After washing the shorts, the edge frayed a lot more, and now I would like to hem them. I don't want to take off a lot of length. I just want a more polished edge. I haven't done a lot of sewing, but it can't be too hard. What's the easiest way to do this? I'll need to do it by hand.