To answer your question - I recommend you do create a new library for your content.
The best place for this is in your Users / folder, so that it's easy to include it in a backup routine. I have all my libraries in my Users / folder under a folder called 3D Libraries, each library with a parent folder (which in Poser will be the Library name) and then the Runtime folders within each of those.

By the way, what version of Poser are you using?

"If I were a shadow, I know I wouldn't like to be half of what I should be."
Mr Otsuka, the old black tomcat in Kafka on the Shore (Haruki Murakami)