I'm still a newbie to this forum and its conventions. Where would be the appropriate place to post a piece of work with wich one needs some help and that is still very much a work in progress?

Depends if it's a short story or a novel. If it's a novel, post it in the novel section. If it's a short story, select a category and post it there.

and if it's non-fiction, post it in that section... same goes for script, poetry, et al.

The simple answer to your quesion is that all works for review must be posted in the Review Room workshops. That is what they are there for.

If you wish to post completed pieces that are NOT a work in progress, then your blog is a more appropriate place. Everything posted in the Review Room is for dissection.