The Offspring are a band that mainly uses 5th chords, their chord structures have always been colorful and fast. If you are just learning 5th chords you will find offspring songs difficult, when you can comfortably play their songs then you have mastered your 5th chords.
Intro Riff
The only help I can give you when learning this intro riff is "take it slowly", I have always seen students rush this song and try to get it up to speed, all you are doing is learning your mistakes. If you play the riffs in this song slow enough that you know exactly what the next note is, then you'll learn it at a quicker pace.