Master cylinder or?

Ok I Have a 1985 Toyota Corolla SR5 4ac engine.
Ok about a week ago the clutch was working great. Then a couple days ago I noticed that the clutch engages when I press really low to the floor. No pressure till its almost on the floor.
I called up my friend and he told me to add tranny fluid 75-90wt. I then opened (per his instructions) up the shiftknob area and noticed that the fluid was pretty low. It took 1 whole bottle to fill it up. I then tried and drove it and noticed it was pretty much the same. At times when I get to a stop I can't even shift it to first. Then I turn off the engine pump it (clutch)about 20 times and notice a little difference. But then it gets loose again towards the floor. Let me know what you guys think. I really need to get this fixed. Im thinking I need to replace the slave cylinder as well or do you think I need to bleed it? How do I bleed it correctly?
THanks