I started lifting dumbbells a few weeks ago. The exercise that I've been doing is the on where you start out holding each dumbbell at the side (with your hands hanging). Then you lift each dumbbell up to your chest and slowly back down. Is it enough if I do just this exercise? Or do I had to do other dumbbell exercises as well in order to have better looking arms? If so, could you please post a website with pics showing it done? I'm new to this whole weight-lifting thing so I really don't know stuff off the top of my head. Having a pic makes it easier to see how it's done. Thanks in advance.