Hi there wolfshape!

There are a lot of ways to make face changes to a character in Poser 6. For example you could click on the face room tab and play with the face in there. Also textures that you apply to the character give it a different look.
Morphs are another way to change a character into your own.

What exactly are you going for? There are lot of different terms that can be used to explain.. If you give some more details on  what your trying out, I'm sure the good folks here will pipe in to assist  and give you some great advice and links.

  :)