Here is the basic song minus the solo.  The song is in G.  The G on the sixth string (fat E) third fret can be played either with the middle finger or thumb.  I find it easier to play it with the thumb.  This leaves all other fingers open to play the treble part.  If playing with the thumb just slide from the sixth string first fret (F) into the G, sixth string third fret.  The way it's written here looks more like a hammer-on.  This first intro part basically repeats with some variation to the treble parts. The song follows a typical 1-4-5 chord progression.  So you start in the third position (G) for the I chord and then go to Bb and play the same pattern.   Then move to C and then go back down to G.  There is a part later in the song that goes back and forth from Bb and D. 

The solo is basically in the G pentatonic scale but there are some G Dorian notes here and there. 

Here is a wav of me playing the first part. as written. Below are is a  G Dorian scale chart for reference.  Remember that the G pentatonic is the same only that Dorian adds a few more notes.