Hi Zoey, welcome!
I love Green Day too, and might I recommend another easy Green Day song to learn? Warning.
Warning has just 3 power chords - A D and G - and a simple repeating pattern: AAAA, DDDD, GGGG, DDDD. And you can scale up as your ability increases - start with a single strum of A, D, G, D, then as you improve you can do two strums of each chord, and eventually work up to 4 strums.
Anyway, have fun and enjoy the journey!
