Capo on the third.
[ Tab from: http://www.guitaretab.com/j/justin-bieber/331846.html ]
Am. F. G
E------------------------------------------------------3------------------------|
A------0--------------------3------------------------------2--------------------|
D------------2-------------------3----------------------------------------------|
G--------------------2----------------------2--------------------------0--------|
B--------------------2----------------------1--------------------------3--------|
E----------------0-------------------1---------------------------3--------------|
