E Major Key Signature

Going from the key of D to the key of A, we added a third sharp to the key signature, G#.
Now going up another 5th from A to E, we add a fourth sharp to the key signature, the 7th note of our new scale, D#.
So the key signature of E is four sharps, F#, C#, G# and D# and the notes that make up the E major scale are E, F#, G#, A, B, C# and D#.
 

Guitar Chords in E

Guitar chord diagrams above and degree of scale, chord name and notes below make up the key of E Major.
I Major = E Major - E G# B
ii minor = F# minor - F# A C#
iii minor = G# minor - G# B D#
IV Major = A Major - A C# E
V Major = B Major - B D# F#
V7 = B7 - B D# F# A
vi minor = C# minor - C# E G#
vii- = D#- - D# F# A