For example, if you have a song in the key of G (usually, the first chord of a song gives away the key of the song) with the chords G, C, and D, you could change the song into the key of A. You would just put a capo on the 2nd fret, and play the chord shapes G, C, and D. These chord shapes will now sound a whole step higher. They will sound like the chords A, D and E.
When learning more about using a capo, there are 2 basic ideas to understand. Chord shape, and chord sound.
No matter what fret you have the capo on, when you play a G chord shape, in your mind you will always think of it as a G chord. This is a G chord shape. If you were to capo the guitar at the 2nd fret and play a G chord shape, then the chord sound would be that of an A chord.
This is the main idea of using a capo. You are using familiar,
maybe even easier chord shapes to get the chord
sound of less familiar, more difficult chords. If you
have a Bb chord in a song, you could put the capo at the 1st fret,
and play an A chord shape. But you will get a Bb
All this sounds wonderful but, how do i use a guitar capo?