Watch the Drop 2, 3 Voicings: online guitar lesson by Brad Carlton from Guitar Lab: The Golden Arp

The 3rd inversion drop 2, 3 voicing of the Add 9 chord is derived from the 2nd inversion close voicing form. There are two layouts of this on the fingerboard which are identical. You could also view them as 2nd inversion major triads with the 9 (2) added on top. I'll show you some fingering options in the video so be sure to explore all of them. One final note; although not presented in the video, you may play the lower three voices (of the form which involves strings 1, 3, 4 and 5) over on strings 2 through 4 with a barre. Be sure to try this. (See example 16 diagram)