Help me please!

[deadmans]

I dont have a pc around right now and i have very little time to search things like these..
Anyway i used to do gym last winter but at spring i got injured (bmx) and got some belly fat and so on,
i v rode bmx all summer and soon il go to gym at winter,so i am wondering how i could "balance" my body because my legs look fat.
Should i do diet when i go to gym and so on, i try to check it when i am around a pc Even this was wrote in a hurry...
shortly: What should i eat and how should i train if i want to keep my muscles and lose some fat from my legs (i know i need to lose it everywhere,i cant only lose it from legs)
I ll be thankful for any help!And i will check in!