Hi Eileen, I don’t think you have the right idea re Poser in that you do not use PSP to make the 3D models, that takes a modelling program to model them, then rigging them and other processes. I don’t do that, I purchase my models from one of the Stores, download them and install in Poser (that is the program I use). However, some clothes for instance you can texture easy yourself in a graphic program from the template. The model skin textures need more skill to look good.
PSP or Photoshop comes into it for post working your finished images, adding backgrounds or making one, and for or other elements you might wish to add.. It could be also used for making scrap book elements.
Poser is not free but the DAZ Studio program from DAZ 3D is. They have heaps of models for sale to use in it but it is an expensive hobby. Another good place to look to see what it is all about is HiveWire3D, the store, the forum and their image gallery of images done by members especially.
PSP or another graphic program is just one of things Poser or DAZ Studio artists need. Hope this helps