My new electric wall oven has a 3-wire with ground (black, red, white & ground). The previous oven was attached to the current circuit which is #10 2-wire with ground (black, white, ground). How do I make this connection to run both the 110v & 220 volt components on the new oven?

Can't guess the voltage of the old oven.

Your going to have to run a new 4 wire service to the new oven with the proper gage wire and connect L1 and L2 to a properly rated breaker. Your also going to have to connect Neutral (White) and (Ground).

Transformers can be used to create the 120 V if the old oven was 240, but you would need to know how much 120 is needed in amps or watts.

The old oven may have been all 240, or used the ground as neutral. I am not sure if you are allowed to do that with a new oven. Since my range is wired up that way, I may fix whatever goes wrong rather than buying a new one.

You do not need to change the feeder cable, as advised.

Simply connect the white and ground from the oven to the bare in the cable.

This is only allowed for existing cables for ovens, cooktops, ranges, and dryers.

You do not need to change the feeder cable, as advised.

Simply connect the white and ground from the oven to the bare in the cable.

This is only allowed for existing cables for ovens, cooktops, ranges, and dryers.

Just so I understand... I would connect the white, black and ground cables to their correct port on the oven, and do nothing with the port where a red wire is supposed to go? Thanks

You misunderstood him. Black and red are hots and must go to their terminals. Connect the white to bare. The white should be connected to the metal cabinet or green wire somewhere.

OK, unfortunately I don't have the red on the wire that runs to my breaker. Only black, white and copper ground.

White is not likely a neutral and goes directly to the breaker, but you'll have to check.
If white does go to the 240 breaker. both ends should be taped red.

If, indeed it's a 240 line white and black will be going directly to the breaker, Bare will be connected to ground in the breaker box.

This is why your supposed to tape wires the color they are supposed to be. This happens when using switches and in your case when the cable contains white, black and bare and it's a 240 V circuit.