Putting rear tire back on my bike?

dealing with a 2005 diamondback mr lucky 24 (idk if that helps).



so i took my bike apart to clean it and oil it.to get the tire off, i took the U-brakes off (also to clean). now i put the tire back on: it has two lugnuts on each side like normal, but it also has these pieces on each side that i was told adjust the chain tension. so i tightened down the u-brakes, and put the tire and chain back on, and i just cant get it so the brakes arent rubbing against the rim. how would you go about doing this with the brakes and chain adjustments? could i have messed up the brakes taking them off?Putting rear tire back on my bike?
You need to check the return spings on the brake arms and make sure they are in the same place on both sides.

http://bicycletutor.com/adjust-v-brakes/Putting rear tire back on my bike?
Assuming the rim isn't bent or out of true, the first thing I would check is to see if the wheel is in the frame straight. Since you have chain tensioners, this will be easy. First, find the tight spot in the chain. Then, keeping the pedals in the spot where the tight spot is, loosen the axle nuts and tighten the screws for the chain tensioners on both sides little by little until the wheel is centered in the frame and the chain is fairly tight. Tighten the axle nuts and spin the pedals to see if there is no binding. If there is, back off the axle nuts and release the chain tensioners on each side an equal amount, and then repeat the above procedure. This should help.

The next thing I would check is the brake pads. You want to make sure they are hitting the rim flush or so that the leading edge of the brake pads are touching slightly before the rest of the pad. If after you check the wheel for being centered and the pads aren't hitting the rim in the center of the rim, adjust them so they are and are again, hitting flush. If this doesn't help then it sounds like when you took your u-brakes off, you released the spring tension and now there isn't enough tension in the brakes to pull them away from the rim. The spring adjustment is made by slightly loosening the bolt that holds the u-brake arm on the brake post, then take a 13 mm wrench and turn the brake spring cap so that you feel resistance; try turning it counter clockwise first, and if that is still keeping the pad against the rim, then turn it the other way. Do the same with the other side if necessary, and remember, a little turn goes a long way.

If you are unsure of what you are doing, there is no shame in taking the bike into a bike shop and having them fix the brakes. It won't be expensive (shouldn't be more than $30) and it will be done properly. For future reference, just squeeze the brake pads together and undo the straddle cable (you will see that one side of the cable that goes to both brake arms has a head on it that you should be able to take pliers to to remove that end from the slot in the brake arm) instead of taking the brakes completely off. That way you won't unwind the brake spring. Good luck!