You need a spanner, a nipple, and a piece of tube.....
You have a bleed nipple of both callipers, you need to slip on a spanner (usually 8mm) and then connect a piece of hose to it. Undo the nipple slightly, squeeze the brake lever in an then righten the nipple before releasing the brake lever. Do this repetitively with both callipers and the jobs done, I would advise you check that all banjos are tightened up properly first and that you have no leak.
Make sense?