This is a transcription of J.D. Crowe's backup playing with the Bluegrass album band. It has all those fancy vamping and "Foggy Mountain Special" style licks. For each measure there are other backup licks you can switch around to get a sense of how to put some variation in your backup. You can inject classic Scruggs vocabulary along with J.D.'s playing, which is also heavily based on Earl's. There are also many simple backup options in the lick switcher. These are there to show you don't have to play super fancy to play solid backup. It's actually better to play simply, dynamically appropriate, and with rock steady time. It also gives you the option to fall back on if some of the original transcription is just too tough for you at the moment.
Throughout the tab you will see the letter "x" appear above the tablature. This marking indicates the note directly below is a muted, or "ghost" note. That means you don't hold down pressure all the way with your fret hand. You just keep your finger barely touching the string, or release pressure immediately when picking. Your goal is to get a percussive sound that doesn't ring out.