Turn both sofa sections upside down and press the edges together.
Center the the sides of each connector across the space between the two sections and mark the screw holes. Use two connectors for each section.
Fit an electric drill with a bit one size smaller than the connector mounting screws and drill a pilot hole through each mark.
Place each connector over the pilot holes and secure them with mounting screws.
Turn the sofa sections over, position them in the desired location and line up the connectors. Press the sofas together until the connectors click.