With your right hand, strike drum one and then drum three. Bring your left hand across your body, and strike drum one and then drum three while you bring your right hand over the top of your left arm.
With your right hand, strike drum two and then drum four. Raise your right hand to allow your left hand to pass underneath, then use your left hand to strike drum two and then drum four. Again, use your right hand to strike drum two and then drum four while bringing your left arm over your right arm and across your body.
With your left arm, strike drum one and then drum three. Repeat the sequence of hitting one and three with the right, then one and three with the left, while bringing the right arm over the top of the left arm.
Go through these motions slowly and concentrate on the feel of the arm sweeps. Practice at a very slow speed until it feels comfortable and natural.
Slowly increase the speed as you practice the move.