how do you replace master cylinder on a 2000 Chevy lumina

Master cylinders are usually similar so there should be a lot of YouTube videos out there. You need to disconnect the supply and return brake fluid lines to the master cylinder, then unbolt it from the vacuum booster housing. Recommend you also get the bench bleed kit with the new master cylinder to bench bleed it prior to installing it. Put everything back, bolt it up, and then start bleeding your brakes from the passenger rear, driver's rear, passenger, and driver's side brakes.

http://www.youtube.com/watch?v=MusYyVZq-r0