The melody is made of by the riff which goes something like this: 
 

    
        Abrir tablatura
        
    
    
E--------------------|---------------- 
D-------------------|---------------- 
G--------------------|---------------- 
D-0-0h2p0-0---0-2--|--0-0h2p0---0--- 
A-3-----------3------|3---------3---3- 
E--------------------|----------------
 
 
Other than that its 2 chords. 
 
 
     F           C         F      C      F  C  F  C 
They didn't have you where I come from 
      F        C        F      C      F  C  F  C  
Never knew the best was yet to come 
F      C          F        C      F  C  F  C  
Life began when I saw your face 
      F         C            F   C      F  C  F  C  
And I hear your laugh like a serenade 


[Refrão]
F   C           F          C      F  C  F  C  
How long do you want to be loved 
      F     C         F        C     F  C  F  C  
Is forever enough, is forever enough 
F   C           F          C     F  C  F  C  
How long do you want to be loved 
      F     C               F                           F C F C  
Is forever enough cause I'm never, never giving you up 
 
I slip in bed when you're asleep 
To hold you close and feel your breath on me 
Tomorrow there'll be so much to do 
So tonight I'll drift in a dream with you 
 
Chorus 
 
As you wander through this troubled world 
In search of all things beautiful 
You can close your eyes when you're miles away 
And hear my voice like a serenade 
 
Chorus 
 
Chorus 
 
Cause I'm never, never giving you up