Probably the simplest of hems is the double fold hem. It’s just the edge of the fabric folded over twice (to encase the raw edge) and then stitched in place. Heather from The Sewing Loft devotes a post to this often used hem, giving tips and tricks for getting it to look just right. Go to The Sewing Loft to read how to make a double fold hem.
[photo from The Sewing Loft]