Turn off the weed eater and disconnect the spark plug or battery
Remove the trimmer head cover
Take out the spool
Remove any remaining old line
Cut a new length of trimmer line to the correct size
Insert one end of the line into the spool hole
Wind the line evenly in the direction shown on the spool
Leave the required amount of line free at the ends
Thread the line ends through the spool eyelets
Reinstall the spool into the trimmer head
Replace the cover securely
Reconnect the spark plug or battery
Test the weed eater briefly and trim the line if needed