the edge of the brake pad on one side is too close to the rim.i tried using screws to give the rims more space but everytime i brake slowly it goes back too close to the rim.

Do you have caliper brakes (that mount with a bolt above the top of the tire, adn the brakes arch over the tire) or cantilever/v-brakes (that mount on posts in the bike's frame, below the level of the rim)?
Given your mention of the screws, I assume you are talking about the latter.

Sometimes spring tension is different enough, either because of quality control or one of the springs getting bent, that screw adjustment isn't enough. Your options are
a) see if the bicycle frame has multiple holes on the brake-mount post where you can anchor the spring into the frame. This gives some incremental rough adjustment so you can tighten one spring or loosen the other
b) see if you can bend the looser spring so it's tighter. This won't necessarily work out well, but it's worth trying before
c) replacing the brakes (b/c it's hard to find springs by themselves and v-brakes are cheap)

Make certain that the brake cable housing is not pulling or pushing the brake one way or the other.

Going to need some more info. Is this a newish dual pivot caliper with a standard central mount? Does it have a tiny little centering screw coming out the top on one side? When there is "too much room" on one side, do the pads still manage to hit the rim at the same time? Or does the rim flex as you press the brake?