Only the static pad has an adjustment screw. I find that its best to run the pad as close as possible to the disc without causing any drag.
You adjust the moving pad with the cable, either the cable retaining bolt or the barrel adjuster at the brake lever. make the adjustment so the lever causes bite at a suitable position.
If you have never used discs before, you need to bed the pads using braking heat.
Find a hill, get some speed up and apply the brakes hard but not to skid. Keep speeding/braking about 10 times until the disc is really hot (don't touch, it will burn).
Do one brake at a time.