All the notes you have learned so far have been played by open strings and the first three fingers of the left hand. However, there are other notes which require the use of the 4th finger (little finger). The first of these is the note B on the E String. This note is shown in the following diagram.
This B note is written above the leger line above the staff.
Play this B note with your 4th finger on the E string.
This piece combines the new B note with all the other notes on the E string.