This guitar instrumental is in an open C6 tuning: Low C:A:C:G:C:E which means tuning the Low E down to C, the D string down to C and the B string up to C. The other 3 strings remain the same as standard tuning.
The song appeared on Physical Graffiti, but was written 5 years beforehand during Led Zeppelin's stay at a small cottage in Wales (called Bron-Yr-Aur). That's where their more acoustic 3rd album was inspired and written, but Bron-Yr-Aur didn't make it onto that album (same for a few other songs). Thankfully, it wasn't canned...
The style of guitar here is folk. It involves fast fingerpicking, as usual with the thumb playing the bassline and the fingers picking out the chords / melody.
Make sure to go through the Core Skills on Fingerpicking before attempting this song. Despite the easy intro, there are some very tricky bits to watch out for, and the pace is fast. The main parts of the tune aren't so hard, especially once you get a feel for the fingerpicking pattern. But some of the chord changes can be very awkward. In fact the first main chord change is probably the worst. We'll look at that in a bit.
The fingerpicking follows a fast T123 pattern, but not strictly. There are occasional breaks from this. The good news is that much of the tune uses open strings (such as the intro), which makes the fingering much easier and lets you concentrate more on the fingerpicking side of things right from the beginning. Once you have a feel for the fast T123 pattern, a lot of the rest of the tune will come easier.
However, right after the intro is perhaps the hardest bit to play in the whole song. This D chord isn't too bad once you get used to switching to it with your fretboard hand, but both hands have a real challenge with the subsequent pull off / chord change.
This one little part really takes some skill because you need to pull off and as the pull off releases the open E note - pick the bass note with your thumb at precisely the same time. In other words the bass note of the next chord should sound at the same moment as the note you just pulled off to (or just fractionally after it). This is some typical Jimmy Page mastery, and will be a real challenge. Once you can do that part, the rest of the song will be well within your grasp.
If that pull off / bass note bit seems impossible - fear not! What most people do when they play this song is just skip that dastardly bass note altogether. The pull off is much more important as it is a defining part of the melody line. Nobody will notice if you skip the bass note, as they will be following the melody line. And bear in mind how fast the tune is played - a skipped bass note really is not a massive affair. At normal speed it is a fraction of a second.
If you want to play the song the easy way - do the pull offs, skip the awkward bass note. When you get more natural with the fingerpicking pattern, it will become much easier to start working on putting the tricky bass note in on time.
