If you use 12 volt bulbs, you will need 12 volts.
You can get 12 volts from the PC power supply, or you can use a "wall wart" that converts the 120 volts to 12 volts. The 12 volts can be AC or DC, incandescent bulbs dont care.
Then it is simply wiring the two bulb sockets in parallel. then wire to the 12 volt source.
Check you this pic, connect the two bulb sockets as shown, then the two wires connect to the power supply.
Do not connect the bulb sockets directly to 120 Volt AC! Unless the sockets and bulbs are rated at 120 Volts (which they are probably not), it can be a very dangerous shock hazard, due to the sockets insulation not rated for that high voltage.
Feel free to ask if you have any more questions, thats what we do here...