If you are using default Poser and/or Zygote models/stuff, you can do whatever you want with the pictures (because the license contract allows it). However, if you use FreeWare stuff you should carefully read the enclosed read-me's, because a lot of the creators restrict the usage of their work to non-commercial purposes - and everyone should respect this. If in doubt, it's never a mistake to contact the creator and ask for it.