They go in the same structure as the runtime folder inside your poser folder

Runtimegeometries    (.obj files)
Runtimetextures           (.bum, .jpg files)
RuntimeLibrariesposes       (.pz2 and .png files)
RuntimeLibrariesProps        (.pp2 and .png files)

Oh, and don't forget a readme file that gives your email contact incase of difficulty, as well as any terms of use such as if it can be used only for personal use, or if it can be used for commercial use. Also indicate if you are allowing the file to be redistributed, or if it can't be.

Hope that helps  :)

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi