Understanding the scales on the guitar: The minor scale

As I promised in the previous post now I'll be writing about the minor scale.
How tthe minor scale is made?
The formula for the minor scale is as simple as the formula for the major scale.
Here it is:
2  1   2    2  1   2   2
Or in the key of C it look like this:
C  D   Eb   F   G    Ab   Bb    C
   2    1    2     2    1      2    2
What is that minor scale that has no flat or sharps?
Well, the A minor scale is the only minor scale that has no flat or sharps. Thats because it's relevant to the C major scale.
How do you know which scales are relevant?
This is really simple. Just take one scale and five steps above it it's the relevant scale.
Let's make it more clear. You take the G major key and start to count:
 G: A B C D E
Now for the G major the relevant is the E minor scale.
How many different minor scale exist?
There are a few variety of the minor scale: natural minor, harmonic minor and melodic minor.
The natural is the one that I wrote up in this post.
To make a harmonic minor you need to raise the seventh note a half step when you go up and down the scale.
So the C harmonic minor will look like this
C D Eb F G Ab B C

The melodic is done by raising the the sixth and the seventh a half step when you go up the scale and return to the natural minor when you go down the scale.
So the C melodic minor scale will look like this (I'll go up and down to see how it is):
  C - D - Eb - F - G - A - B - C (up the scale)
  C - D - Eb - F - G - Ab - Bb (down he scale

You can search the YouTube for backing tracks. It's really useful to improvise on music to develop your creativity.