Firstly - this is only the basic guitar, so you can sit alone and play it with only one guitar, so no fancy guitar harmonics in it. Second - These chords are taken from www.GreenDayChords.com - thanks! At last, remember this: At the time this was recorded, Green Day didn't really care about tuning, they just tuned after each other, until it sounded good. So unless you take your time tuning it after the music, it won't sound 100% right, but it's somewhere between E and Eb tuning. Intro: D C (guitaretab.com)