a basic sleeve is shaped like this. you'll need two of these, and i recommend using a fabric with some stretch.
If you don't know how to make a sleeve, I strongly suggest you either BUY a pattern with sleeves, or cut apart an old shirt to make a sleeve pattern yourself, because they are tricky, goofy-shaped little dudes, and I can not instruct you on how to make one other than the advice above.
add an inch or so to each measurement, unless you have very stretchy fabric and want very tight sleeves.
the top bell curve corresponds with the measurement of your shoulder-armpit.
the widest part should correspond with your upper arm measurement.
fold it in half and sew the sides together.