My ceiling box has a white, a black and a copper wire. My light fixture has 2 black wires. Can I use either of the blacks as hot and what do I attach the copper

See if one of the black wires has ridges on it, or a stripe, or identified in some other way. If so, this goes to the white wire; the other to the black wire.

Look for a green screw on the light fixture--if there is one, that is where the copper wire goes. Alternatively, look for a screw that seems to not be holding two pieces of metal together. If you have either of these screws, I'd simply coil the wire up inside the ceiling box. Just make sure it won't short out against the other connections.

Good luck,
WallyH

The ground wire should be attached to both the light and the box. Use a short piece of wire from the light and from the box. Wire nut these 3 wires together and push to back of box.

If nowhere on light to attach ground, just hook up the one to box

Chuck