Okay, the easy answer LOL.

In poser6, load in say, Jessi, the female p6 figure.  Make sure you load the one thats "FBM" or full body morphs.  Once loaded, select her head in the workspace, and voila, a set of dials will appear for her head to your right.  You can move those dials, which will change facial features.

Not satisfied?  Not enough ethnicity?  No problem!  Click on the folder tab up top to go to the face room!  Now, in the face room, look to your lower left, lookie, more dials!  These will litterally re-arrange her face, and add ethnicity, play with the dials until you have what you like, then on the upper right, click "apply to figure".  Go back to the pose room, and voila, you have a morphed enthnic Jessi!

You can do that with any of the Poser 6 people!  However, figures you buy, or get from free stuff, will have morphs or injections you can select, to get the dials in the pose room, yes, its just that simple!