Google - is B7 note considered very a high note? Is B7 lower or higher than B4?

C4 is considered "middle C". On a full size piano, C4 is right in the middle.
Stand in front of the keyboard. The C that's right in the middle (right in the
middle of the name of the piano) is C4. Vocally, that might be considered high
for some singers, and not so high for others. It depends on their vocal range.

C7 is a LOT higher than C4. 3 octaves higher. And that's high for just about
any singer.

B is the note just to the left of the C notes.

On guitar, it's a little confusing because guitar music is written an octave lower than it really is. Middle C on guitar is an octave lower (C3) than on a piano. The note is
played on the 3rd fret of the 5th string. But in concert pitch, middle C would be the note on the 1st fret of the 2nd string.

There is a logical reason for this. If guitar music was written the same as piano, for example, most of the notes for a song would be way above the staff. So the music is dropped down an octave so the notes start a little bit below the staff, and go a little above it.

Hope that helps. If not, drop me an email at wayne at thewaynereedconnection com

Wayne