Have a search through the 2D freestuff here for portrait backgrounds - one of those could well be appropriate for this. You want something with some interesting variation in it, but not too distracting. If you have Poser 5 or above you could also try experimenting with the clouds node in the material room.

Quote - I'm not exactly sure what a texture map is though.  Is that what UV Mapper is used for, or do you just mean when I have everything else textured?

People use different names for the same thing here, which can be confusing. :) A texture map is just an image file which is applied to a 3D model to colour the surface (see also transparency map, bump map etc.) It's called a colour map in some parts of the 3D world. What you get with UVMapper is a template - something that will guide you when making your own texture maps.