The guitar has vast possibilities. Chords can be voiced in a multitude of ways but more often than not we find a couple that work for us and that's enough. In this lesson we'll take a one octave scale and harmonize just three chords from it. 
 
In E major, the pitches are E F# G# A B C# D# E. You arrive at this by taking the starting pitch, E, and then using the following formula of whole steps and half steps to get the remaining notes...
 
W W H W W W H.
 
So the second note, F#, is realized by going a whole step higher than E and the 3rd note, G#, is a whole step higher than that, etc.
 
A chord is a combination of three or more notes sounded at once no matter how discordant or otherwise pleasant the sound. Each note of a scale [in this case E major] is the foundation of a three note chord called a triad. The notes of a triad are found by taking the root note of the chord E, the 3rd G# and the 5th B. Here's a more graphic illustration...
 
E F# G# A B C# D# E
 
Because of the range of the guitar, not terribly unlike it's linebacker monster of a big brother the piano, it stands to reason that provided that the player knows where all of the notes of the fingerboard are, any chord can be played in a vast number of ways all over the fingerboard.
 
The same technique can be used to find the Amaj chord and the Bmaj chord.
 
E F# G# A B C# D# E F# G#... 
 
The A triad, using A as the root note, is spelled by taking the 3rd and 5th notes higher than A in this key and sounding them wherever they can be found on the fingerboard. The same is true for the B chord.