How do I see what's in the downloads folder? When I plug the phone into the computer I can view the contents of the downloads folder but when using the phone directly I can't find the download folder.
You cannot access folder contents directly from your phone. Every file in that folder can be accessed only by the apps that supports their format. Pictures in the gallery, Music from the music app, Pdfs from Adobe Reader etc etc.
Anything that gives you access to all content on a folder shared by many/all apps is a potential threat to the security of your content.