I am trying to animate this simple guy walking, and i already set the skeleton up (no kinematics), and i try to key the guy, move his leg and then key again... but the problem is, after i move the guy's joint, the guy changes in all the frames... i want it to be with his leg down at key 75, and his foot up at 85. When i move the foot and key at 85, i go back and discover that what i changed was also affecting key 75, and so on.... gets frustrating... do i need to key all the joints??? and should i key the skeleton of the guy?? (i tried them both and they do the same thing..)

help