Need Tips On Losing Weight

Ok well see i'm trying to lose some weight..I dont really feel comfortable saying exactly how much I weight but its not good..I want to lose a good 50 pounds though so thats my goal..And ive made sure that losing that much isnt going to harm me in any way..But I just want things to be different for next year which will be my senior year in hs..So I can finally feel comfortable in my own skin and feel comfortable wearing tighter clothes and such..So yeah I got a tredmil thing in my room, its a manual one so u gotta do all the work to keep it moving which is a good thing I guess..But I just need tips on how I can do it fast...But healthy..My goal is to try and lose atleast 30 by the end of the summer I hope..So yeah I mean I just want to know what foods I should have, and what I should stay away from and stuff, i'm not rich tho so I cant get tons of healthy food cos that costs money but I mean just simple stuff, and what sort of exercises should I be doing?