Again, take the battery out to start the proceedings. Push the tabs to remove the gray cap. Now remove the black spool that holds the line. To wind the line, you have a little hole in the spool. Put the line (about 1 inch) in the hole and roll it in the opposite direction. Keep rolling until you get to the edge of the outside lip. Now, you will see a hole on the spool retainer to come out of the line. You should line up the line and put it through the hole. Place the spool back to the retainer, keeping the gear head at the back. Put back the gray cap.