As you know, it is possible to play the same note in more than one octave. Here is a new C note played on the A string. It is played with the second finger slightly lower (back towards B) from where you would place your finger for a C # note.
This C note is written in the third space of the staff.
Play this C note with your second finger on the A string.
Now try this example which combines the new C note with other notes you know.