The E minor triad, more commonly called the E minor chord, is a minor triad consisting of the notes E, G and B. Here it is on the treble clef staff:
... and on the piano:
Here is the E minor chord on the bass clef staff:
As a minor triad, the E minor chord consists of a minor third plus a major third. The interval from E to G is a minor third, while the interval between G and B is a major third.
If the root of the E minor chord—E—is the bass note (i.e., the bottom note), then the chord is in root position:
If the third of the chord—G—is the bottom note, then the chord is in first inversion:
If the fifth of the chord—B—is the bass note, then the chord is in second inversion. (B is called the fifth of the chord because the interval from the root E to B is a fifth.)
If the notes of a chord are played one after the other, the chord is said to be arpeggiated. Here are the standard fingerings for arpeggios of the E minor chord. Make sure you learn these fingerings!
(If you don't understand the below notation, you should start with my How to Read Sheet Music course.)