You "tone" by building muscle, which means in order to really firm up your butt and thighs, you need to hit the weights, or at least the weight machines (personally, I prefer free weights, but they can be tricky and intimidating.) Things like dumbbell lunges and squats are good for your lower body, and you can do them at home or at the gym.
Shape.com has a decent, fairly easy workout routine that they call "
cellulite-busting strength moves" if you're looking for a place to get started. I like this workout because it has both gym and home options, so if you don't have time to go to the gym, you can do the same thing at home with absolutely minimal equipment (a set of 10 and 15 lb dumbbells) It also has pictures. Everyone loves pictures.
As for losing your gut specifically, there isn't a way to target fat loss to one general area. Your body prioritizes fat loss in whatever order it's genetically programmed to do, and unfortunately there's really nothing you can do about it. Just eat sensibly and exercise more so that you create a caloric deficit, and as your whole body shrinks, your stomach will too.