O come, O come, Emmanuel, and ransom Captive Israel
By the hymnal, that's what we have here. The melody note and a harmony note, in most cases. Consider "come", the first note past the pickup. That's an E and a G. That implies an E minor chord, which, as the staff has one sharp on it, meaning G major or E minor, should come as no surprise. But that isn't an easy thing to fret. So, inspired by Ritchie Blackmore's recommendation to follow the horn players because they can only play one note at a time, I dropped the harmony and just played the melody notes.
If I was Ted Greene, I'd play more than the chords, but in context, I'm one voice among many, so it wasn't crucial to bring the whole of the song to life. I will tab that out and append that later, but I have some stuff to pack so I'll do that later. Santa brought a video camera to the household, so I'll show you how I play it later, too.
Also, Merry (belated) Christmas and a Happy (premature) New Year!