Chromatic harmonica 

is a great, under-rated instrument; and in some ways, easier than diatonic (you don't need to learn to bend notes to play all the notes). SAMPLE VIDEO: Chromatic Harmonica Lessons.Chromatic Harmonica: Hole/Note Layout.

Diatonic vs. Chromatic Harmonica

Here is a comparison of the diatonic and chromatic harmonicas. It should help you confirm that you have selected the correct type of harmonica for the style of music and type of sound that interests you. Scroll down the page for details.