This excerpt teaches you a vital technique called "tongue blocking."
Your guitar can handle most of the chording, so let’s look at ways to play single harp notes. A traditional way to play single notes is with “tongue blocking,” in which your tongue blocks three of the four holes that your mouth is covering. Usually the unblocked hole is on the right side of your mouth. You can start a major scale in the key of your harp by first blowing on hole four, then drawing on hole four, then following that pattern on holes five and six. Finish the scale by drawing and then blowing on hole seven.
Play the scale over a progression in C, such as C–F–G or C–Am–F–G. Neil Young played his popular guitar-and-harp song, “Heart of Gold,” using the chords Em, C, D, and G with a G harp. You can play it in C using the chords Am, F, G, and C. You can develop coordination by playing the single-note scale on your guitar along with the harp scale. These activities will not only help you learn breath control but will let you become familiar with the layout of the notes in the major scale.