Treble and bass clefs can also be modified by octave numbers. An eight or fifteen above a clef raises the intended pitch range by one or two octaves respectively. Similarly, an eight or fifteen below a clef lowers the pitch range by one or two octaves respectively. A treble clef with an eight below is the most commonly used, typically used for guitar and similar instruments."
Meaning guitar notes are written one octave higher than the piano notes.You are reading guitar music sheet indicating 8 under clef sign.
If the same music sheet is used for piano,the 8 number will be removed.
On page 6,your first note is a "half note" "e" placed on string "1".
If same note is played with out 8 on treble clef, it will be one octave below, played on low 4th string pressing fret 2.On page 9, "Old Macdonald" piece, just check "E" whole note,representing one octave below.
Example of octave.
C Scale is written as,
One octave higher C scale will continue after B on higher pitch.Same for one octave lower C scale will be played on lower pitch.
Hope this may help.