The following example contains the chords G, C and D.
When changing from C to D, do not lift your third finger off the string, but slide it up to the fourth fret. Only touch the string very lightly as you do this. This technique is called using a slide finger. This example is written in rhythm notation using quarter note strums and finishing with a half note strum.
To play this G note, place the fourth finger of your left hand just behind the fifth fret of the 1st string