E to E all on the white notes is not really a scale. You need F# to get the scale of E minor. The only scales which can be played on the white notes alone are C major (C to C) or A minor (A to A).
It's rather complicated, but if you consider the keyboard as a whole (black and white notes together) each key is a semitone higher than the one before it. Whichever key you start on, a major scale will ascend as follows: tone, tone, semitone, tone, tone, tone, semitone. A minor scale goes tone, semitone, tone, tone, semitone, tone, tone.
Tone means go up two keys, semitone means go up one. This probably sounds horribly confusing and is probably much simpler to demonstrate than explain.
As an example, suppose you start on G. The sequence for the major scale is G A B C D E F# G. The minor scale goes G A Bflat C D Eflat F G.