The site is open to people to explore their gender identity however they chose, if learning mannerisms makes them feel better about themselves then it's perfectly valid for them to ask.
To answer your question Spookie there are many subtle and not so subtle differences between the postures, body language and mannerisms of men and women. I would recommend spending some time in a public place just casually observing the way women move and interact as a useful starting point. Keep in mind the spectrum is wide, women sometimes do things that are generally regarded to be masculine and vice versa.
The other thing is not to take on a mannerism just because someone else is doing it, it has to feel right and natural to you otherwise it won't look very normal. For me, once I was presenting as female, I just found myself more able to move in a way I had been holding myself back from all my life. It comes more easily than you expect once you are no longer pretending to be a gender you are not.
