I'll just give you the short answer.  If you want the long answer, we can do that later.  The difference between major and minor scales is where the location of the whole steps and half steps are located in the scale.  In this particular instance A minor shares all of the same notes as C major.  C Major is C, D, E, F, G, A, B, C.  A minor has exactly the same notes, but starts on A.  So the notes for A minor are A, B, C, D, E, F, G, A.    I hope that helps. 

If you google Circle of Fifths you will find a diagram of that name which is a very helpful music theory tool.  I recommend finding that and keeping a copy around for instances such as this one. 

OK.  In addition, to what I said before.  There are actually three different minor scales.  The Natural Minor, which is the one I explained.  The Harmonic Minor and the Melodic Minor.  They are 3 completely different scales.  If the music is in A minor, without any other words, it means it's Natural minor.  That scale is A, B, C, D, E, F, G, A.  Most likely that's the one your after.