Left unattached, sectionals can develop gaps in between each piece as they shift, proving frustrating for adults, potentially dangerous for children and pets, and giving your living space a haphazard, unfinished look. Stand in front of the first two sections. Push them together so that the male side of one side lines up with the female side of the other. Move to the opposite end of the configuration. Repeat this process with the two pieces, lining up the brackets, lifting the male side and locking it into the female side.