Using a fish tape, pull the electrical feeder wires through the feeder pipe. Leave enough wire to get to the opposite side of the panel. That way, there will be plenty of wire to make the connection anywhere in the electric panel.
Bend the two black wires to shape them for easy installation to the main breaker. In this photo, the main breaker is located at the top right of the panel. Strip the wire only enough to make the connection to the main breaker terminal lugs. Excess bare wire leaves a safety hazard where the wires can come in contact with other wires and cause a short circuit.
Connect the neutral wire to the neutral buss. The neutral buss is located on either side of the breakers. It is a silver-colored bar with many smaller screws and connection points. It also has a larger hole for the feeder neutral wire. The neutral wire is the wire marked with the white phasing tape.