I think you'd probably be better off looking for a forum dedicated to the type of art you plan to do rather than one dedicated to Photoshop then, because a forum about Photoshop is pretty generic and will no doubt be more about the program than the artistry.  I can't remember the name of it, but years ago when I first got a Wacom, I came across a forum where it was strictly 2D stuff, comic art and drawings, and although I never bothered to join I used to read it a lot.  And over the years, I've noticed the different types of comic art tend to generate their own communities with their own forums and stuff, so for a genuine appreciation of the type of art you do, those are probably the best bet to show your work I reckon.

You might also have the opportiunity to sell your art to people who are interested in that specific type of art.  It's a bit like the fetishes out there, they all have their individual communities so I suppose it's no different for art and comics.