full sleeves: Measure from the top of your shoulder to your wrist/ where you want the sleeve to end.
cap: these are between 1-3 inches in length are modest comparing the sleeveless and tend to be more stylish as well.
if option is not given add notes to the order that you want cap sleeves.
3/4 : these can be from your shoulder down of elbow or below elbow, measure the length and choose the number.
short: usually are 4-7 inches in length, 5-6 should be fine if you aren't sue of length.