How do you go about grounding 2 prong outlets

You need three conductors, Hot, Neutral, and Ground.
The difference between the neutral and ground is the Neutral Carries Current, The Ground, connects to all other grounds, and if wire came loose, or something was shorted to ground, it would trip Breaker and not become live.
You need 3 wires for best operation and safety.

There is a possibility that the ground exists in the metal box and is attached to the box, so all that's really required is:

1) Replace the outlet (best choice)

2) Use a 3 prong to 2 prong adapter and attach the ground screw. A cheap outlet tester will tell you if it has an open ground. (If this passes, I suggest choice #1)

If there is no ground wire available in the box you have two choices as per the NEC. Pull new wire with a ground to the box or install a GFCI outlet. Do not install a three prong outlet if it is not grounded.