Watch the 4 Notes-Per-String Forms online guitar lesson by Brad Carlton from Guitar Lab: The Golden Arp
Example 4 will show you the tab and diagram layouts of Add 9 arpeggios in 2nd inversion. This means the open string will function as the third. An easy way to determine the root of these forms is to remember the root will always be in the 8th fret. The available arpeggios from 6th string through 1st string would then be CAdd 9, FAdd 9, BbAdd 9, EbAdd 9, GAdd 9 and CAdd 9.
This 4 notes-per-string layout of the 2nd inversion Add 9 arpeggio will always be as follows: The open string will be the 3, the 5th fret will be the 5, the 8th fret will be the root and the 10th fret will be the 9(2). Again try to see the complete Add 9 arpeggio in terms of a shifting along the string axis of the original root pos. form.