Here are the charts for E minor guitar chord. This is by far the easiest guitar chord to learn. It's only 2 fingers!
The first version of e minor to learn on guitar is the one in open position. You play this chord by placing your 2nd finger on the 5th string 2nd fret, and your 3rd finger on the 4th string 2nd fret. Let all the other strings ring openly. The chord diagram says to use 1st and 2nd finger, but most players use 2nd and 3rd.
Next is my favorite version of e minor. It's played as a bar chord on the 7th fret. To play this version, bar across the 1st thru 5th strings with the 1st finger. Then, place your 3rd finger on the 4th strong 9th fret, your 4th finger on the 3rd string 9th fret, and your 2nd finger on the 2nd string 8th fret. I love the way this version sounds. It has a really sweet sound to it.
Another version of Em that looks hard to play, but is really easy to play is this one. It's played by barring all strings at the 12th fret witht eh 1st finger. Then place your 3rd finger on the 5th string 14th fret and your 4th finger 4th string 14th fret. Use it to spice up your jams with a different sound.
Here is a version of Em that is common in fingerstyle guitar. Since the 6th string is played and the 4th and 5th aren't, it is the perfect chord to hit the bass note with your thumb while picking up the higher notes with the 1st, 2nd, and 3rd on the right hand. This chord is played by placing your 1st finger on the 1st string 3rd fret, 2nd finger on the 3rd string 4th fret, and 3rd finger on the 2nd string 6th fret. Play the 6th string open, but do not play the 5th and 4th strings. Playing it with a pick is hard, so you may opt to only play the 1st 2nd and 3rd strings. However, if you are fingerpicking, it is easily played with the thumb and 1st three fingers.