First of all, an E minor chord has an "E" in it. "E" is the root of the chord. The root gives the chord it's name, and is usally (but not always) the lowest note in the chord. Here is Em again and then the "E"'s separately.
note that our chord sounds pretty plain. (OK theory mongers, I know it is not actually a chord yet-you really need three different notes for a legitimate chord)