Creating a simple rolled, top stitched hem is really easy to do!
Here are a pair of pants needing to be shortened. Decide how wide of a hem you want (here I'm doing a 1/2" hem.) For a 1/2" hem, double it because you will be turning it over twice. So I will need 1" hem allowance. Mark the new hem and then add the 1" hem allowance. Cut off the remaining fabric. Press up 1", then fold down 1/2" and press. The raw edge should now be enclosed.
Stitch close to the fold. All done! See the finished hem below. (Below left shows outside of hem, right shows inside of hem).