Back in the day, this is how brakes were bled: First, you replace the master cylinder and then fill it with brake fluid. Then, you go to each brake - one by one - to bleed the brake (get all the air out of the system). To do that, there is a little "pip" near where the brake line attaches to the calipher. You loosen the pip. Then, someone else pumps continually on the brake pedal. Air and fluid shoot from the pip with each pump of the pedal. When air stops coming out, and only brake fluid starts coming out, the person holds the brake pedal down on the last pump while the pip is tightened. Then, you go to the next brake and repeat the process. Once, that is done to all four brakes, then there is no air in the system, and it works great. It takes two people: one at the pip/caliper and one on the brake pedal. If it isn't working great, then there is still some air in there somewhere and you have to repeat the process. You also should top off the master cylinder with fluid a couple of times during bleeding the brakes.
YouTube has videos of people hooking a tube and bottle to the "pip" to bleed the system. You can watch those videos and do that, or just do what I said.