Play the B note with the third finger of your left hand.
Play the C note with the fourth finger of your left hand.
Now that you are using all four fingers to play notes, make sure you have one fret spacing between each finger as shown in the photo below.
Remember to place each finger directly behind the fret to avoid buzzing and to create the best possible sound.
Example 29 uses all the G and D string notes you have learnt.