when i start me jeep and put it in drive it make a really high pitch noise and gets louder the more gas i give it. some one said it might be a lose belt but i just wanted to make sure,also if you have any tips on how to fix it would be great. thanks

 

open the hood and see if it's coming from the serpentine belt....
if it is coming from the serpentine belt, try tightening it.