When you got the poser installer from posersoftware.com there were two files you needed to download install poser11.exe (.pkg if you are on a mac) and posersupport.exe (or pkg). I assume you ran installposer11 first and then posersupport. If you followed the defaults this will have set up a folder called poser11 content in your public documents folder. This is where the poser content that is displayed in your library is stored.

Just under the two files you should have downloaded from posersoftware.com/downloads there is a link which says "Download Additional Content Files (License required)". Click on this and enter your serial number and that will give you access to the additional content.

To install content so you can see it. I would suggest you add a new library to load the content.

I have explained how to do this a few posts up from this post. Now for freebies and purchased items. First look in the zip file and check that one of the first folders you see is called runtime. If it is you can go to the menu item in poser "install from zip archive" under files. Click on this and a window will open, navigate to the zip archive, select it and click on ok or open, I can't remember what its called. This will open a drop down menu, select the library you have added and click on ok. This will install your content, and you should be able to see it.

If the runtime folder is not one of the first folders in the zip file, you need to unzip the zip file (in windows select it, right click and choose extract all files) and then merge the runtime with the runtime you created when adding the library (you will have to do this with the additional content)

Hope this helps