You should have some figures, clothing and hair that was included with Poser. I believe there was another installer for the older content.

You can find a lot of free stuff, or purchase what you want from Daz, Poserworld , renderosity or any of the other poser sites. 

You can modify the figures by adjusting the morphs that come with them, or use an add-on character.

Poser hair tends to be one style, with some variations, so for changing styles you use a different hair figure. Hair is expensive so search freestuff, and look at whats on sale in the various stores.  Runtimedna has some good stuff.

www.digitalbabes.jp has some free hair which is very good.