Wrap the exposed metal of the receptacle with electrical tape. Wrapping the metal prevents sparking if the receptacle needs to be removed again for repair. Also, if a foreign metal object were to hit the exposed metal while the receptacle was live, there is a chance it can arch and throw sparks. Gently push the wires back into the box, then line up the mounting screws with the corresponding holes and tighten. Be sure to install the receptacle with the neutral side up. If anything were to fall onto the receptacle, it would hit the neutral and ground wires first and eliminate any chance of an arch. The half-round slot at the front of the receptacle is the ground slot and the larger slot above the half-round is the neutral. These should be installed at the highest point of the wall. Cover the outlet with a plastic plate. Turn the power back on at the circuit box. Test the outlet by pushing the test button in the middle of the receptacle. If the reset button pops out it means the outlet is live.
If you have any questions or fears about working with electricity, call a licensed electrician. This type of work can be very dangerous, and there's no use risking your life just to save a little money.