I'm self taught on theory, so, I second-guess a lot of things I read in theory books. So, I understand that for something to be in the key of A, it will contain chords from the A maj. scale: A Bm C#m D E F#m G#dim. Let's say a song is in A, and it's chord progression is: I, V, II, V, VII, I. Someone says, play this tune in the key of C now. Would the chord prog. now be: C, G, Dm, G, Bdim, C ? Is that right? Is this what it means to transpose a song?