Gather new strings, a string winder, wire cutters, and a tuner
Loosen the first string until it is slack
Unwind the string from the tuning post
Remove the bridge pin if your guitar uses bridge pins
Pull the old string out of the bridge
Remove the old string from the tuning post
Repeat for each string, or replace one string at a time
Insert the new string into the bridge hole
Reinsert the bridge pin if applicable
Pull the string through the tuning post hole
Leave a little slack for winding
Wind the string around the tuning post
Turn the tuning peg to tighten the string
Keep the wraps neat and below the post hole
Tune the string up slowly to pitch
Repeat for the remaining strings
Stretch each new string gently by pulling it upward
Retune all strings after stretching
Trim excess string ends with wire cutters
Tune the guitar again after a short playing session