Getting in shape for cheer?

So, its summmer! I reallly want to get back into shape for cheeer! It starts prettty sooon soo I have like a litttle over a month to accomplish this! I'm going into highschool, so this means a new team, new expectations, and new requirements. I already know what the requirements are to be on my highschools team, and I know how to do them. I'm taking tumbling classses with my friend starting in a couple weeks even though I already know how to do a roundoff backhandspring and more. (Taken 4+ years of gymnastics) But I want to get my backtuck soon! Well, anyways! I just want to know what I can do NOW to get in shape, and lose just a couple of pounds. I weigh about 115. What kind of exercises can I do to build some muscle? Also can someone give me a specific diet plan to folllow for a majority of the summer? I feel like I'm eating too much junk now. :b Thanks for alll your help! :D