On an acoustic guitar with nylon strings, you twitch the string around itself at the bridge and insert through the machine head which you then turn to tune the string.

1. Insert string through its hole in the bridge.
2. Loop it under itself and back.
3. Twitch it around itself 2 to 3 times for thick strings or 3 to 4 times for thin strings.
4. Pull the twitch tight.
5. Run other end along neck and thread it through its machine head. Pull tight but slack it back out 3 to 4 inches to allow it to loop around the cylinder several times.
6. Turn the machine head until the string is tight and then tune it.

On an acoustic or electric guitar with steel strings, you will find a small ring in one end.

1. Insert string through its hole in the bridge.
2. Pull tight.
3. Run other end along neck, and thread it through its machine head. Pull tight but slack it back out 3 to 4 inches to allow it to loop around the cylinder several times.
4. Turn the machine head until the string is tight and then tune it.

Important! If you have an acoustic guitar, make sure it is designed for steel strings before installing steel strings on it. If you have a guitar meant for nylon strings, and you install steel strings on it, you can very easily damage the guitar. The bridge will come loose from the body, or in worse case, if you have a guitar of poor quality, the neck can actually break loose from the body.