The melody of O Christmas Tree by Glee Cast runs 220 notes across 59 bars, 2:47 long in A at 70 beats per minute. The tab sits almost entirely in the first two frets, one note at a time — no chords to barre and no strumming pattern to keep up with. A piano backing track plays the chords and bass underneath, so the line you are learning sounds like the record even at half speed.
Prefer to strum and sing it instead? O Christmas Tree chords and lyrics.