At
developers.facebook.com open your application that you've created. Then you should see a menu like this on the left hand side. At the bottom of that menu you can see the section labeled "Products". If you're already at Step 15 of our application setup guide, then you should have "Facebook Login" listed there under products, like this:
Click on that "Facebook Login" and you should see the "Settings" section that Step 15 is describing.
If you don't have "Facebook Login" already listed, you'll see this:
Click on "Add Product" and select Facebook Login from the available list and choose the "Set Up" button. Then go through Steps 6-14 of our application setup guide again.
I hope this helps, but let me know if you're still having trouble.
-Melissa