Theory problems

Can someone explain what does it mean to play chord over scale? Let's take for example Am chord (notes: A, E, C) and A minor pentatonic (notes: A, C, D, E, G) So when playing Am chord in A minor pentatonic you use all 5 notes (A,C,D,E,G, but accent A) or you use mainly A,E,C (chord notes) but for better sound you add some notes from A minor pentatonic scale?

Thanks

anyone?

Say you're playing a C major scale. The chords that would fit the scale are C, Dm, Em, F, G, Am, and Bdim. Those aren't the only ones you can use, but these fit best, because they all use notes on the C scale. Use what sounds right to you.

You can apply that to pentatonic scales also, but I'm not so good in that area.

heh.. i dont really understand how this work either.. but im goin to college for a music degree this year and ive got a guitar and a piano class..

so maybe i can answer this question in a semester. (see you then ;) )