What can i do to get fit over the summer?

ok so there's only 2 weeks left of school for me and over the summer i wanna get a fit body! i'lll probanbly start today! i'm 13 and i weigh about 125 and i'm 5'4 so i'm not fat pretty skinny actually. but i have jiggly thighs and its annoying to have great looking legs while standing up then when sitting down to have jiggly thighs. my arms also jiggle and my stomach is sorta flat but its a little poochy and it does jiggle to so bassically i need to build muscle. i eat pretty healthy everyday (rice and beans for dinner) but i eat some bad stuff which i will cut down on everyday and i will get my mom to buy healtier stuff but for now i really need some exercises i can do! i already know sit ups will work but what else. i also have some weights and an ab roll i can use (you just roll on it and it makes abs its worked for both of my brothers i used to use it but gave up lol). i don't want abs though just a hard flat stomach nice legs that don't jiggle to much but are toned and fit arms.