agree with sweetest_potato, reduce overall body fat (no such thing as spot reduction, the body stores it where it chooses. the first place to store fat is the last to let it go) and strengthen the muscle that's there. look up some good core exercises and watch the diet (meal plan, I prefer to call it). do some tricep extension exercises. grab some kind of weight (anything that's small and has weight will do) lie on your back and point your weight to the ceiling, lower the "weight" to your shoulder, keeping your elbow stationary then straighten out again. If you can do more than 12 repetitions, grab something heavier. (a half gallon milk jug with a screw cap filled with sand works well in a pinch. then switch arms. do a couple of sets of these every couple of days and your arms will begin to tone up.