Read your manual for types of fluid. Or on your fluid container it should say what fluid to use.
There should be a grease nipple on the brake caliper. You need a spanner to open the screw. You pull in the brake lever and open the screw at the same time and the old fluid should squirt out. Close the screw quickly after it. Try to not let air bubbles into the lines. All times have the lever pulled in when you open the screw. fill the container up with the new fluid and keep bleeding the line until you can see the new pink fluid or what ever colour it is come through.
Obviously you only bleed cars not the various brands of MTB brakes.....
Read the manuals on the brakes to determine the method. Eg for Hayes, you DONT pull the lever, but squeeze fluid in from the bottom (caliper) and let it out at the top (brake lever).
Squirt, lock off, then test lever, pumping a bit to loosen/release air bubbles, then bleed some more until all air is gone.
This means that you have to have a FULL syringe at the bottom, no air in the tube connected to the bleed nipple, avoid dripping ANY fluid on your caliper less you contaminate the pads, possibly your small ring spanner over the nipple before the tube, A correctly fitting tuba at the lever end with a bottle or something taped to your bars to catch the overflow fluid etc...
Not hard, but if done wrong can cause issues.And then the realisation that you probably should have taken it to the LBS anyway etc....
Lots of threads here in Farkin already on how to do the various brands.....
