PZ2 files are poses, which you would find in Poser xRuntimelibrariesPose... Where x is your version of Poser.

However the only thing poses usually have to do with clothing is in applying textures to them. Clothing is found either in CR2 or PP2 files (Poser xRuntimelibrariescharacter... or Poser xRuntimelibrariesprops...) I have no idea why WW would be looking for poses.

Wardrobe Wizard comes with several excellent video tutorials, and I'd strongly advise watching those before diving in.