I still don't get the whole flat/sharp thing. Seems needlessly complicated.
Sharps and flats are used in scales to maintain intervals depending on what type major or minor scale you're playing in. For example, the key of "C" needs no sharps or flats because the intervals (made up of whole-steps and half-steps) are "perfect" for the major scale format. A major scale can be described like this:
whole-step/whole-step/half-step, whole-step/whole-step/whole-step/half-step
C(whole)D(whole)E(half)F(whole)G(whole)A(whole)B(half)C
As you can see E-F, and B-C are naturally accurring half-steps.
These are naturally occurring intervals in the key of "C", and that's why it needs no sharps or flats. In any other key, sharps or flats are used to maintain the correct intervals, or "natural" interval of the major scale.
For example, in the key of "A", sharps are used to raise notes to maintain the correct major scale interval, so it looks like this:
A-B-C#-D-E-F#-G#-A
This is why the key of "A" is written as having three sharps. Playing it on your fretboard may help you to see this more clearly. the same applies to the "flat" keys. Try writing out the key of "F" for example, and you'll find it uses only one "flat". Which note is flat-ed? How about the key of "Bb"? Which three notes are flat-ed?
Each scale, whether it be major, minor, phrygian, iolian, etc., has it's own set of unique intervals, and using sharps and flats is how those unique intervals are maintained. That's what all the scale practicing is about - learning those intervals! Hope this makes it a tad bit clearer....
