Hi Peter
Great to hear you're enjoying your scope.
With an untracked dob, imaging is quite difficult, but it can be done. Use this guide to get you started:
Astrophotography with a Dob
I'm not sure if there's an easy-fit adapter for a 900nc like with the older ToUcam Pro II, but you could try Mogg Adapters. Otherwise someone else might chime in with some help.
Cheers