Help on getting toned!

Hey so I'm 16 and at a fairly average weight (120lbs.) and well sized, but I do have little clumps of weight that I'd like to get rid of, such as my hips and thighs. I don't have a major amount of time to go to the gym though, which is an issue. 

I can't run due to problems with my knees, so I was told that the elliptical machine was good for me? I just don't know how much or what setting I should do on it to help specifically what I need.

I would like to know what I can do to tighten up my abs, thighs and lose the muffin top! At the gym and any little things I can do when I'm stuck at home.

Anything is appreciated, thank you!