Unfortunately (and this is a lesson I've had to learn the hard way!), there's no way to "spot reduce" fat. The only way to get rid of fat deposits is to create a calorie deficit by healthy eating and exercise so the body is forced to burn fat for fuel. Where you lose the fat is really up to your body based on your build. For instance, I lost weight very quickly in my waist (although I don't do any specific "waist" exercises) and calves but still have a pretty big lower belly and big thighs despite lots of ab work.
On the other hand, lifting heavy weights "to failure" (until you cannot do any more repetitions with that weight) is a great way to add muscle to your arms. It won't make the fat go away
, but my upper body lifting has greatly improved the way my shoulders and biceps look
(even though I do still have the icky dangly fat under my arms). Eight-pound weights might be fine to start with, depending on your existing strength. When you get to the point where you can easily do 12-15 reps without your muscles getting tired, up the weights a bit to challenge them more.
A great place to start with info about weight training is Stumptuous.com (http://www.stumptuous.com/weights.html
Hope this helps!