To install a line in the weed eater, you will have to follow the following steps: First, you will have to support the weed eater and then access its spool. There will be a spark plug that you will have to disconnect for safety. Now you will have to remove the weed eater's spool. Make sure you are removing any grass, debris, or dirt which is present in the tool. Use a sharp scissor to cut an 18-foot long trimmer line from the filler spool. Use the line and wrap it around the weed eater's spool. Now assemble the spool.