Using a capo is a common way to change keys without learning new fingering or re-tuning the entire guitar. Some keys are more difficult to play in with a regular guitar tuning. The capo makes playing intricate songs in odd keys simpler by allowing you to use familiar fingering. You can also use a capo to alter the key of a song to better suit your vocal range.
Tune the guitar. Use an electronic tuner to set the pitches to an E A D G B E pitch progression, starting from the first string, which is the thickest one. Play the first string and turn the appropriate knob. Check the tuner and continue to raise or lower the pitch until the tuner indicates the pitch is in tune. Silence the first string and repeat for the rest of the strings, making sure to silence the previous string before tuning the next one.
Clip the capo firmly onto the neck of the guitar on the fret of your choice to alter the key you will start in. Make sure the capo is perfectly perpendicular to the neck of the guitar and covers all six strings.
Count how many frets from the top you placed the capo. The capo will raise the pitch of the guitar one half step for each fret, beginning at the very top. If you are playing in the key of D, placing the capo on the first fret will modulate the song to D#/Eb. A capo on the second fret will cause you to play in the key of E. If you move the capo to the fifth fret, playing the chord patterns for the key of D will now allow you to play in G, all while using the same fingerings you would normally use for the song in the key of D. This modulation will continue on down the neck. By the time you reach the twelfth fret you will be back in the key of D, but an octave higher than you started.
Make sure the capo is clipped on all six strings tightly and is completely straight. Remember that B to C is one half step, and the same applies with E to F. All other natural tones have a whole step in between, which is the equivalent of two half steps. A sharped note is a half step above the natural note; a flatted note is a half step below the natural tone.