In this video from pazzmanmusic we learn how to play the harmonica in the key of G. Draw on the 1, blow on the 2 and blow on the 3. Then draw on the 3. A bit of a bend draw. Then walk it down by drawing on the 2 and then drawing on the 1. Then he goes on to play a riff where he blows on the 1 and 4 holes and covers the 2 and 3 with his tongue. The 2 draw is the same as the 3 blow. The distance of the notes are the same for each of the keys, the tons is just transposed higher or lower.