Here are some free youtube tutorials. Some are for older versions of poser but they go over the basic ideas. Warning, there is some poser character nudity.

https://www.youtube.com/watch?v=6xNIv2Qs6pE

https://www.youtube.com/watch?v=ZEwUrmkpARU

https://www.youtube.com/watch?v=i60QxB0boHs

Hope these help you get started :)

Edited to add this one from Smith Micro about the Material room specifically. Also there are some video tutorials here, under Community, Tutorials :)

https://www.youtube.com/watch?v=--ZDrBtxrZQ

Edited again to add Renderosity Material room youtube tutorial...

https://www.youtube.com/watch?v=zcVCI6CNz-4

The dust settled, thinking "what a fine home, at least for now" not realizing that doom would soon be coming in the form of a vacuum cleaner.