I can play harmonica and guitar quite well. It took me about a decade to get good at the guitar. It took me a week to get good at the harmonica. You see....each harmonica has a KEY....B, E, A, D, C, F, etc... If you're playing a blues song in A you pull out a harmonica in the scale of D and start playing it - it won't be long before you figure out that if you draw in at about 1 cm from the left you'll get the one chord with some cool bends....try it.