Play this C note with the first finger of your left hand just behind the first fret of the second string.
This is a C note. The note C is written on the third space of the staff.
Notes written above the middle of a staff usually have their stems going down. Notes written below the middle line of the staff usually have their stems going up. The stem for the B note can go up or down.
A riff is a pattern of notes that is repeated throughout a song. To play this riff, play bars 1 to 8 twice, as indicated by the repeat sign, then play bar 9.