I should have done step-by-step photos, but these are so easy you don't need them anyway, as long as you have very simple knitting knowledge and can do a single crochet border.
1. Cast on 30 stitches with Cascade Fixation (a nice elasticized cotton) on size 7 needles. Work in garter stitch (that is, knit everything) until it's long enough to reach around your hand at full-stretch (the garter ridges will be running vertically up your wrist, not around.)
2. Sew together into a tube, leaving an inch or two unsewn at one end.
3. Do a single crocheted border in a contrasting color around the bottom and top edge (including the slit.) I just used scrap wool from my stash with some random hook that was about the right size. Improv is the name of the game, here.
4.Put the cuffs on so that the slit is over your thumb, and figure out where you want the buttons... I just used a hodgepodge of any red buttons I had around. Sew 'em on in a line.