Turn off the weed eater and disconnect the power source or remove the battery
Wear gloves
Lay the trimmer on a flat surface
Remove the trimmer head cover
Take out the spool
Remove any old line
Cut the new trimmer line to the correct length
Insert the line into the spool holes or slots
Wind the line onto the spool in the direction indicated on the spool
Leave the required amount of line ends exposed
Place the spool back into the trimmer head
Thread the line ends through the eyelets
Reattach the trimmer head cover
Pull the line ends gently to confirm they feed properly
Reconnect the power source or reinstall the battery
Test the weed eater briefly