Watch the Close Voicings: online guitar lesson by Brad Carlton from Guitar Lab: The Golden Arp
There are three root position close voicings of the Add 9 chord on the fingerboard. This is because the chord contains four notes: The root, 3rd, 5th and 9th; since we're dealing with a one note-per-string layout, our string groups will be 1 through 4, 2 through 5, and 3 through 6.
Example one presents these three voicings and while difficult or impossible to play with just one hand, they are worth studying. In the video you will learn how to play them with two hands when practical, and you'll learn how to play fragments of each voicing.