Take the cushions off the couch. Drape one sheet over the base of the couch. Push the sheet down along the arms of the sofa, along its back and along the seat.
Smooth the sheet in place and secure with the pins. Allow a bit of give in the sheet so that it doesn't snap out of place when someone sits on the couch.
Lift up the sheet and draw a line of glue along the bottom edge of the back of the couch. Quickly put the sheet back in place. Hot glue dries quickly.
Lift the sheet and glue along the inside back of the couch, all over the seat top and on the arms of the couch. Put the sheet back in place before the glue dries.
Place one of the couch cushions on top of the other sheet. Pretend that you are going to wrap the cushion with the sheet as if it were a present. Cut the sheet to fit the cushion. Repeat with any remaining cushions.
Fold one side of the sheet over the cushion. Place a line of hot glue on the edge of the sheet and quickly fold the other side over, pressing in place. If there is an extra sheet flap, secure it to the cushion with glue. Fold one of the open sheet sides into a triangle and fold onto the top of the cushion, just as you would wrap a present. Glue in place and repeat with the other open side. Place the cushion on the seat of the couch with the glued side down. Repeat with any remaining cushions.