Theory problem

I tried to post a table on intervals but when I hit submit it screwed it all up. Here is the link.

INTERVAL GUIDE

It is in section 2.1 (Interval guide). My question is, this works in the example they have shown which is "C" but if you try it in "A" it doesn't work because there is no B#. Can anyone explain this?

Simple mate,
B#, Cb, E# and Fb do exist. They are merely hidden behind the B, C, E, and F's.
We have them to fit the scales so we can use the notes properly. When creating our seven note major scale we cannot repeat note names (There can't be a C and C# in the Key of C#) so we must substitute them with other note names.

Remember that D# and Eb are the same? Well they share the same frequency, the same sound. The two differing names are to allow the sound to function whenever needed.
Here's a list of the note names and which ones they share(double flats and sharps are left out),

E - Eb/F - F#/Gb - G - G#/Ab - A - A#/Bb - B/Cb - B#/C - C#/Db - D - D#/Eb - E... etc.



I am quite tired right now so feel free to ask about any confusion, for I'm sure this is a little vague. Best of luck.

Interval......Name....................Note
-----------------------------------------------
1..........Unison (root note)........C
b2.........Minor Second..............Db
2..........Major Second...............D
#2.........Sharp Second.............D#
b3.........Minor Third.................Eb
3..........Major Third..................E
4..........Perfect Fourth..............F
#4.........Augmented Fourth.......F#
b5.........Diminished Fifth...........Gb
5..........Perfect Fifth.................G
#5.........Augmented Fifth..........G#
b6.........Minor Sixth..................Ab
6..........Major Sixth..................A
#6.........Sharp Sixth................A#
bb7........Diminished Seventh.....A
b7.........Minor Seventh.............Bb
7..........Major Seventh..............B
8.........Unison (Octave higher)...C
b9.........Minor Ninth..................Db
9..........Major Ninth..................D
#9.........Sharp Ninth.................D#
------------------------------------------------

I think I found a way to make this work, I had to fill in all the empty spaces. How would the key of "A" work on this table? What would the sharp second be?

It would be B#, which is the same as a C, but it is named as a B because in A the 2nd note is always a B, and the 3rd note is always a C-something, eg, min3rd = C natural, maj3rd = C#

Thanks guys. This stuff is really kicking my ass right now. It seems like one of those things that when you learn all the rules on how to apply it everything just falls into place and becomes very obvious. At least thats how I hope it is.

Yeah, it is really quite simple when you've got it, it's kinda like learning a new language.

I found picturing the fretboard a huge help in understanding it. I'm sure there are other tricks as well.