Conrats! Weight loss won't help, but building muscle will. If you have cellulite on your butt and back of your legs, you need to build muscle there by doing ballet-type workouts (Physique 57 and Bar Method are killer). Or use gym equipment for hamstring curls and butt blasters and what not. Regularly change up your reps and sets and the order of exercises so you continue strengthen and build muscle in that area. Another thing that will help is consuming foods that will assist with maintaining and rebuilding connective tissue, like gelatin, bone broth, and MSM. Avoid sugar, which causes cross-linking and breakdown of collagen, which will make your cellulite look worse.
Oh, had to edit to add this: Vitamin C synthesizes collagen, and builds connections between amino acids and collagen, strengthening tissues. So make sure you're getting adequate amounts. Your best bet is to eat a lot of vitamin C rich foods, since your kidneys like to excrete pretty much all vitamin C if you take around 500 mg in one go.