Hi and Welcome, I assume you are asking about the full version of Kontakt3 and not the Kontakt Player. It looks a little different than Kontakt2, but functions much the same way.
When you open your new version of Kontakt , just below where it says Kontakt in the upper left, you should see a tab that says files and if you click on it, your computer's directory should be listed. If you navigate to and open up the drive where you have GPO installed, you should find it listed there. If not, then follow the directions below.
You may have to click on the database tab just to the right and then click on the "rebuild database" tab. You can specify which drives you want Kontakt to search, and also which formats to include: Then click on "rebuild" and go have a beer or a cup of coffee while Kontakt searches your computer. Once it has finished the search, you should be able to navigate to and load whatever instrument or samples you wish. Good luck! John