You will have to give more details- I unzip the files-they usually have a structure similar to what you should end up with in your own Runtime. If you go to Applications-you should find a subfolder of Pro called PoserPro2012 Content- inside that is Runtime. You drag and drop the items from the runtime from your download-into the appropriate folders. Then restart Poser. Your library has your files. If you drag and drop while it is already running-you need to refresh your folders in the Library window. Select the folder-then a little icon appaears on the right called Refresh.

If you still dont see it-you've likely put something in the wrong destination. Easy to do!