leaking oil

i CHECKED MY OIL AND WAS 1/2 QT LOW. (THE CAR DOES BURN OIL.) I ADDED A FULL QT AND THEN FAILED TO REPLACE THE OIL CAP. AFTER DRIVING A LITTLE i NOTICED OIL ON THE DRIVEWAY. i REPLACED THE OIL CAP AND NOW AFTER AND THE OIL WAS A LITTLE LOW. NOW AFTER DRIVING I AGAIN FIND OIL ON THE DRIVEWAY. WHAT DAMAGE COULD I HAVE CAUSED WHERE DO I BEGIN? i CHECK OIL, PUT GAS IN AND AT TIME HAVE TBL PUTTING AIR IN THE TIRES.....SO i GUESS YOU SEE WHERE MY ABILITIES ARE...THANK YOU!!!!!!