As far as fingering 9th chords go, I usually demonstrate it like this:

Start with a regular B7 chord fingered X21202. Then lift your little finger and flatten your 3rd finger down to form a "mini barre" covering the first three strings. The resultant chord (X21222) is B9. Slide it up a fret and it's C9. Slide it two more, it's D9 etc.

There are other fingerings that may work better in individual tunes, but the X21222 chord shape will do the job 99% of the time.