1992 Other Oldsmobile Models wont keep fluid

My brake light came on a week ago.I put fluid in it and the light went off. After driving fine for over a week, I have to park my car on a very steep driveway. Nose down.I applied parking brake and car was there for about 2 hrs.
I started car and released parking brake. My brake pedal went to the floor. I backed out onto the solid ground and pumped brakes several times. No brakes, no brake fluid, refilled empty fluid resivoir and pumped them again. No brkaes. Fluid was on the ground on and behind right rear tire. Help