I open "Computer" in Nautilus, Ubuntu's file manager.

On the left is a column of names, one of them is "62.8 GB Media" which is my
Windows C: drive. I click on it once, and the main panel shows all the folders.
Now I can double-click on a folder, and it shows me everything in that folder. I
have full control over everything; I can copy, delete, make new files, etc.

Ubuntu and Windows have the same username and password. I don't know if this
makes any difference.