The Time Machine backup access that you are used to depends on software in OSX. The files are on the disk, of course, but the structure is extremely complex and difficult to navigate manually - and you will presumably find that as it's a Mac formatted disk you can't open it in Windows. I don't know if there are programs available to allow Windows to read a Mac disk. If so, all you can do is look through it, or use searching to find files, and try to find the latest version and see whether you can open it. Of course in most cases you will need the Windows equivalent of the same program, if such a thing even exists, so there are bound to be files you can't open even if you can find them.