The lead melody in this song is pretty easy, making it good for beginners. Jim Martin plays the original harmonica melody here on guitar. It's quite repetitive, so there isn't actually too much to learn.

Melody 1 - This is the main melody for the song. It repeats a lot, and isn't too hard - just 8 notes. The trick here is to shift hand positions while the open notes are sounding out like here. This allows you to move your hand into the best position to play the next part of the lick.

Melody 2a - This is a bit trickier. Just break it down into small chunks of a few notes at a time. Practice a chunk until you get it, and then move on to the next. It repeats twice then shifts up to the next part of the melody.

Melody 2b - This melody continues from the previous one and acts like a bridge - i.e. it sets up the return to the Main Melody.

After this just repeat these tune sections all again until...

Melody 3 - Although this starts out with the main melody, it then diverges. This part soon resembles melody 2a and 2b, the timing is the same but some of the notes are higher.

After this, it's back to repeating the main melody over and over until the last part of the song where he switches between the A5 and G major partial chords.