My first tab so let me know what you think. 

Capo 4

       G  D  Em  Cadd9
  E -  3  2  0    0
  B -  0  3  0    3
  G -  0  2  0    0
  D -  0  0  2    2
  A -  2  x  2    3
  E -  3  x  0    x

Sometimes the Cadd9 sounds better with the high E string playing a 3 instead of 0. 
Just something I found.

Intro: G Cadd9 G Cadd9


G           D                        Em                Cadd9
I can't explain, what goes on in my brain,   But it's beautiful and scary baby 
G             D                  Em              Cadd9
I don't know why I can't quite define ,   How my heart beats when I'm with you 
          G                                                    Cadd9
But it's somethin' like summer,    And somethin' like Saturday night 
                                                 Em
Somethin' like getting drunk for the very first time 
                           Cadd9               D
Free fall, cannon ball ,   Into the river no clothes at all 
          G                                              Cadd9
And it's somethin' like sunshine hearing my name on your lips 
                                              Em
Like a song and goes a little something like this 

WOAH OH 
                    Cadd9
I don't know what it is for sure 
          Cadd9                           D                   G      D     Em     Cadd9
But this somethin' like somethin' feels nothin' like nothin' before 

G                   D                        Em            Cadd9
I would be a millionaire if I could sell the air ,  That I walk on when I'm near you baby 
G                     D                            Em
I, I wouldnt save a dime,    I'd spend it all on time 
    Cadd9
Everyday the rest of my life would be 
G                                             Cadd9
Somethin' like summer somethin' like Saturday night 
                                                 Em
Somethin' like getting drunk for the very first time 
                          Cadd9                D
Free fall, cannon ball ,   Into the river no clothes at all 
           G                                             Cadd9
And it's somethin' like sunshine hearing my name on your lips 
                                                 Em
Like a song and it goes a little something like this 

WOAH OH 
                    Cadd9
I don't know what it is for sure 
          Cadd9                          D                    G      D    Em     Cadd9
But this somethin' like somethin' feels nothin' like nothin' before 

   G                    D                                Em
No we can't put a label on it ,   Not sure what we would call it 
       Cadd9
But it feels so good 

G                                                 Cadd9
Somethin' like summer and somethin' like Saturday night 
                                                Em
Somethin' like getting drunk for the very first time 
                           Cadd9              D
Free fall, cannon ball ,   Into the river no clothes at all 
       G                                            Cadd9
It's somethin like sunshine hearing my name on your lips 
                                                 Em
Like a song and it goes a little somethin' like this 

WOAH OH 
                    Cadd9
I don't know what it is for sure 
          Cadd9                          D                     G         Cadd9   
But this somethin' like somethin' feel nothin' like nothin' before
                    G
Like nothing before 
         Cadd9                                              G        Cadd9    G
This somethin' like somethin' feels nothin' like nothin' before