The guitar can play chords, which are series of notes played at the same time. Playing a chord on the guitar gives the root note, which is the note from which the chord takes its name, a richer and fuller tone. Play a B major chord, which is more commonly just called a "B chord," by using your full index finger to bar the strings at the second fret of the instrument and using your other fingers to add the other notes.
Hold the guitar as you normally play it.
Press your index finger down over all six strings at the second fret from the headstock. Adjust it so that the tip of your finger mutes the low E string, which is the thickest on the instrument.
Press the fourth fret on the B, G and D strings with your three other fingers, keeping your index finger pressed down. The B string is the second-thinnest; the G and D strings are the two next-thickest strings.
Strum the guitar to play a B major chord.