For about $7 you can buy a DIY brake bleeding kit (plastic hoses and cup) with a cover. Attach one end of the hose to the bleeder screw on the brake caliper and the other end to the cup. Open the bleeder screw and pump your brakes. Be sure to keep adding fresh brake fluid to the master cylinder reservoir as the old fluid in the line is flushed out into the cup. When you have clean fluid flowing thru the hose, tighten the bleeder screw and go to the next wheel.