This Irish folk song goes by a few different names and is usually sung as Down By The Salley Gardens, which has lyrics by W. B. Yeats set to an older melody known as The Moorlough Shore. I first heard it when I was playing with my friend Martha Blackmen, who taught early music at Stanford University. It can be played with may different harmonic progressions and mine is derived from many different ones.
The lesson is a fairly basic arrangement combining the melody with an arpeggio accompaniment and goes over some fundamentals of arranging. There are some important right hand techniques as well, including slightly separating bass notes from melody notes and muting bass strings that shouldn’t keep ringing. There are also hints about making it your own.