1) Pull the 'spout' connector pin (little gray square plug; about 1"x3/4") out of the wiring harness. It is located near the base of the distibutor on driver's side of it.
2) Start the car.
3) Loosen the distributor hold-down bolt (use a shallow socket with a wobbley and a 6"+ extension on a 3/8" ratchet)
4) Rotate the distributor until you achieve the desired setting (10-12*BTDC)
5) Tighten the hold-down bolt while making sure the timing is still at the desired setting.
6) Plug the spout pin back into the wiring harness.
7) Test drive to make sure you don't have engine "ping" under full throttle operation. Adjust accordingly.