Q:

Can we use one scale in another scale (the active scale)?, in which case could we do that?

I play piano and guitar. It looks like there are talented people that improvise in some way that they play in a really different scale than the main scale they were playing on from the start, but after, the original scale remains.
I just know Major scales. I and I also know some other scales but don't know when to use them. 
I want to enlarge my knowledge, so I already thank you guys for your help.

A:

I understand your plight of knowing the scales but not exactly knowing how to implement them into your playing. First, I'll say don't expect the practice to yield results over night. The scales will have to be almost second nature before you start to utilize them in practical playing. The best advise I can give (based on experience) is to start out simple, but focus more on the SOUND of the scale. Of course, you should be very comfortable with the "shapes" and notes so that you aren't thinking about what note to play next which will  then free your mind to really start to listening to the sound. This was an eye opener for me when I was working with the dorian scale (2nd mode of the major scale). If you are familiar playing over a minor chord - which I was - the dorian scale should come pretty naturally as soon as you get the sound of that major 6 interval in your ear (e.g. over Am7, playing A - F#, as opposed to A-F which you find in the natural minor). Using your ears will really help with scalular playing. As Charlie Parker was known to have said, and I paraphrase: "Learn it. Then FORGET  it!" 

