Hello, im having problems with my rear end. I just replaced the bearings in the differential and when i went to test drive it, it sounded worse than when it did before i replaced them. What do i need to do?

Depends on which bearings you replaced. Just the axle bearing is pretty easy. If you changed all the bearing there are a few adjustment that need to be set & then checked by a tooth contact pattern on the ring gear. You get the pinion too tight or the wrong side shims & yea it could sound worse.......

We replaced the bearing on the pinion gear and the carrier bearings

This one could be kinda tough not being there. I'm not sure how you set it up. Installing all new parts you need at least a dial indicator & inch lb torque wrench. Now I've seen guys just put bearing in those without changing gears & be able to reuse the shims & crush sleeve & get away with it.

Not sure when you're getting your noise or what kind of a noise it is. If it's more noticable either accelerating or coasting then more than likely you got the pinion wrong. All the time or on turns, then you are probably looking at the side bearings or axle bearing ( axle bearing would be doubtful unless you damaged them some how installing them)

Im getting a loud roaring noise, before it was just winding. My brother-in-law did all the installing while i was at work. Once i hit 45mph it starts roaring and when i start to brake.

Boy it's tough not being able to drive it or hear it Robby. Best thing to do is, you & your brother in-law go back over it. Just guessing, it sounds like maybe the pinion depth is incorrect & is too deep into the ring gear. A tooth contact pattern would show that. Just put grease on the ring gear & rotate it & see where the pinion gear is contacting the ring gear, should be somewhere near the middle but I'm sure your brother in-law probably knows this.... HTH
Good luck