The color of the wires could vary so please consult an electrician if you are unsure of what the wires in your wall actually are.
The neutral wires (could be white) would go to the silver screw, the hot wires (could be black) would go to the brass screw, the ground (could be green or bare) would go to the green grounding screw. Multiple wires can be slid under a receptacle that has the back mounting option. I would not be able to determine what mounting options are available unless I knew the Cat No. of the receptacle that you are using.
Please feel free to call into our Technical Support line at 1-800-824-3005 for further support.