A Major Chord on Piano
You can easily play an A chord in the root position by placing your 1st, 3rd and 5th finger on A (under middle C)-C#(above middle C) and E with the right hand. (If you don't know the numbers of the fingers go to the Basic Piano Fingering Page.
Follow the The C Major chord lesson If you haven't done so yet to see how the A major chord has the same optimistic or joyful sound as all other major chords because all major chords are built out of the same Musical Intervals.
So just like the other major chords A major is built out of a major third which defines the chord as a major chord and a minor third on top of it (A-C#-E).
If we were to try playing this chord by ear we would probably go to A which is the key note of the chord, skip one white key hit the C note, skip one key again and hit the E note. When we'll play these notes together we'll probably figure that we get a melancholic sound rather then an optimistic sound. So by lifting the C note in half a tone to C# we'll create the desired major chord and a quick test will approve that we play a major chord with a major third and a minor third on top of it.
In the image above the all possible chord inversions of the A major chord are given. Don't know what chord inversions are? Click here to follow the Chord Inversions piano lesson.