Watch the Making Billboards: People, Signs and Backdrops online video.
See the Billboards: People, Trees, Signs, etc. topic.
The 3D people supplied with PartyCAD are not really 3D at all. Rather, for each of these people, there are 16 images and the program displays the 'correct' image as you move around the person in virtual reality.
When normal, 'one-image' people are loaded in the Design Editor, you do not need to worry about rotating them. This is because they will automatically rotate to face the camera in 3D views. With 3D people, however, you can and should rotate the people after loading them. If you do not do this, all such people will be faced south in your 3D views. The little projection on the icons of 3D people indicate the direction the piece is facing... south by default.
The images of the 3D people that are supplied with PartyCAD were created with a program called Poser. You could use Poser or some such software to create your own 3D People. Or, you can take 16 pictures of a friend as he/she rotates and assemble these into a bitmap that can be used by PartyCAD to display your friend in 3D in virtual reality, the same as with the supplied 3D people. To learn more about creating your own people, first master how to make billboards and flat people, then you will be ready to proceed to the fancier stuff.