I have a 200 amp panel, fed from the meter located in the house. I want to add another 200 amp.sub-panel in the garage, how can I connect the two? And if so what size of wire do I use?
Thank's

It is almost certain that the largest feeder that you can pull from that 200A panel is 125A. Check the label inside the door.

Why would you want a 200 amp subpanel in your garage?

This is 562349's second thread on this project and he has not replied to either one.
Let's see if he breaks tradition and does the polite thing and replies to at least one of them.