try this...

play each chord for 4-16 beats

Em X Em X (intro) (the x means not to play for a bar) - 2 times

Em G Em G (verse) - 2 times


Em Em Em Em (prechorus) - 2 times

T--------
A--------
B-0-3-0-3

G G Em G (chorus) - 4 times

T--------
A--------
B-0-3-0-3

repeat verse prechorus and chorus

G Em C D (bridge) (change the drums here) - 2 times

repeat verse prechorus and chorus

repeat chorus

repeat intro

Song would most likely be in the key of G major/E minor (Major and minor keys are pretty much the same thing.)

for example
key of C major = A minor
key of F major = D minor

The progression isn't going to sound very rocking because it uses the first note of the scale often. Also the fifth note of the scale is in the bridge (again taking away the hard rock sound.) It is however a basic example of one type of song using chord progressions.

G is the first note of the scale in the Key of G major so it is called I

Em is the sixth note of the scale in the key of G major so it is called vi

C is the fourth note of the scale in the key of G major so it is called IV

and D is the fifth note so it is called V

When talking about the Key of G major the sixth note (vi) or Em can also be refered to as the relative minor of G major.

For any Major key the vi of the scale is always the relative minor.

For a lot of songs the verse is written using the minor scale and the chorus is writting using its major scale counter part. For the above chord progression the verse is in Em and the chorus in G major.