Long couches and those that are made in an L- or U-shape are difficult to transport, so many of them come in sections. With a sectional, pieces of the couch can be broken up for transportation and delivery purposes and then reconfigured once they're placed in a room. In addition, many have brackets to hold them together underneath or on the sides. If the couch sections aren't connected with a bracket, they will slide apart.
Catch Fork on the Underside
Flip the sectional couch pieces on their backs so you have access to their bottoms.
Find the catch fork and bracket underneath the couch sections you wish to join. The bracket must fit inside the catch fork. If the couch isn't arranged so these two pieces fit properly, you will need to rearrange the couch.
Push the sectional piece with the catch fork so it swallows the bracket.
Push the sectional pieces back on their feet. They are now connected.
Clips on the Side
Space the sectional pieces apart.
Look on each side for either a metal clip or tab. These metal pieces will hold the sectional together.
Arrange the sectional pieces so the clip on one piece is facing the tab on the other.
Lift up the side of the sectional with the tab, and force it into the groove of the clip on the other piece. The sectional couch is now put together.