This is another question: How does the wire come into the home and connect to the panel?
Copper wire can react chemically with concrete and mortar although some sources will claim the reaction is slow enough as to be negligible. In any case, best bet is to drill a hole large enough to accommodate a PVC pipe or similar as a sleeve between concrete and copper. If you have a brick exterior you may find you can't drill the brick so look for a wide spot in the mortar.
On a typical breaker panel, remove the cover and look near the top for the service entry wires. Two wires will be insulated with a third bare aluminum wire connected to a lug near the center of the panel. The bare wire is ground. Any good electrical supply store will have clips & brackets that allow a second wire to be piggybacked onto a service lug. Needless to say, the service entry lugs can smoke your ass in less than a heartbeat so a decent pair of gloves, insulated tools, and a healthy respect for Reddy Kilowatt is a good idea.
Also... Be sure the service ground is securely connected after you're finished 'cuz if that one starts to lose contact your lights and appliances will do some very, very strange things.