Your main panel has 2 separate bars that attach to separate 120V feeds. By attaching a single breaker to one of these bars, referred to as "buses", you get 120V. To get 240V, you need a double breaker that attaches to both bars at the same time. When you install this double breaker, it needs to fit so that the plastic separator tab along either of the hot buses slips down the middle of this double breaker. Is this device a welder or compressor? If so, you only need 2 conductor cable to connect to the double breakers. If this device is a stove, then it may need 120/240V, in which case you need 3 conductor cable. The black and red wires will connect to either half of the double breaker, and the white wire to the neutral bus of the panel. That's where all the white wires and some of the bare copper wires may connect to. If the device is 240V only, you won't have a neutral wire. The black and white will only go to the breaker. The bare ground wire goes to the ground lug, where all the other bare copper wires attach to. You will need 6/3 or 6/2 cable to handle 50A. Since 6/2 is rare, you may need to use 6/3 and ignore the white wire if the device is 240V only. Mull this over and then ask more questions.

6/2 is common in Virginia. They sell it at Home Depot for a couple bucks a foot. It has 2 insulated wires that are each made up of 7 smaller copper wires bundled together. One of the insulated wires is white the other black. It also has a thicker bare copper wire, that is for the ground.

The public library probably has books on electrical wiring and how to do it safely, that would also be a good resource.

John - first thing, before you do anything else, buy a copy of "Wiring Simplified" at the big box store and read through it a couple of times.

I think you need to study up on home wiring before you are ready to tackle this.

I installed a new 50A circuit breaker with my new 120/240 range. I instaledl new 6-3 wire thinking this is the only way to match red, black, white and ground in the panel of the range. I also spent the $40 and got a new receptacle and range cord (also red, black, white and ground) did a continuity check on the cord legs to match color wires on the incoming 6-3 wire. My question is in the circuit breaker. The "guy" at Home Depot told me to put "both" red and black wires into one side of the 50A breaker and the white into the other side, ground the ground wire in the ground buss at the bottom of the panel where the others are and call it installed. Do I need both black and red in the one side of the breaker or just the black. I'm thinking I'll be splitting the 220 to each side (red and black) and using the common to service both feeds. I haven't thrown the breaker yet.............