Pull the sofa at least 1 to 2 feet away from the wall to provide enough clearance to install the risers to the front and back legs. Squat or sit next to either of the front legs of the sofa and slip on a pair of sturdy work gloves before continuing.
Lift the sofa off the floor just enough to slide the riser underneath. If you are incapable of lifting the sofa or if the piece is excessively heavy, enlist a helper. One person should hold up the end of the sofa while the other slides the riser in place. Lower the sofa on the riser and manipulate it to ensure the leg is centered.
Repeat this process on the three remaining sofa legs. Push the sofa back into place before sitting on it to ensure the risers are centered under the legs. If the sofa wobbles at all, examine the risers to ensure they're straight and adjust them accordingly.