Do not allow brake fluid to drain if possible ... change the brakes and then add fluid and bleed the brakes.. same way as you bleed any car brakes.. start at the far corner from the reservoir and keep the reservoir topped up .. and pump 90% of the fluid through by the time you have finished as the fluid goes off/absorbs water in the coming 6 mths .. so no point hoarding it.. just use it to flush now.
I normally open bleed nipple about 1/2 turn with a tube going into a jam jar ending below the fluid level .. give it 6 full slow pumps after you feel resistance.. then close it until it is only 1/8 or less open.. and pressure bleed by pushing down hard for 2-3 pedal strokes.. lock that bleed nipple and move to next furtherest and repeat (monitor fluid levels). When finish I may do another pressure bleed against a just open bleed nipple if I have fluid left (keep a wee bit for topping up). Finally flush water all over brakes area to remove any brake fluid, squirt some anti-rust stuff onto and into nipples and put caps on.
Tip to fill reservoir is to remove the vacuum pipe manifold arrangement (one clip) to get to the reservoir more easily.
While you are at it .. do the clutch too... same fluid but harder to get to the nipple.
Oh and Google will get you plenty.. first hit
http://www.carbasics.co.uk/how_to_bleed_car_brakes.htm