This song is super easy, and I think this sounds correct.
Hopefully you'll agree.


INTRO
E     B     C#m    A


VERSE
       E                           C#m
I woke up today a song was swimmin in my head
       A                           B
and I hummed it to myself as i got out of bed
            E                                C#m
and on the way to take a shower it all just dawned on me
       A                                    B
that a song like this just might go down in history


PRE-CHORUS
E  E7         A       Am      E
I quickly ran back to get my guitar
   C#m         A   B
a pen and some paper


CHORUS
           E                    B
cause this whole world needs an anthem
        C#m                                A
and I'm trying to put the words where they belong
          E                 B
yeah this whole world needs anthem
        C#m                      A
and I'm hopin everyone will sing along


That's pretty much it.  Just keep repeating those changes.