I open the app the document is used in for a list... Numbers for spreadsheets, Pages for docs and I like iBooks for PDF even though I have other viewers.
Question doesn't make sense, there is no "desktop" or file system in the sense you're used to on Windows or OSX.
Perhaps if you'd describe what you're actually trying to accomplish you'd get better help. Plus don't be surprised if there aren't many people surfing MacRumors between late Saturday night and early Sunday morning.