Most programs save everything to the C: drive by default.
Unless its saved to the folder for its own program which would be C:\program files\xxx where xxx is the name of the program, then they are usually saved to C:\ usernamexxx\documents where usernamexxx is your own account, even if theres only a single user account it will have accounts for admin and your name at least.
In the folder C:\ usernamexxx\documents you will also have folders for Video, Photos, Music and My Documents.
Windows will attempt to save files into which it thinks is the most appropriate.
Unfortunately unless you have booted to the operating system then these user accounts arent usually available so if you add the drive as a second drive in a different pc you cant access the information in those folders
This is why I always advise people to take note of where windows wants to save files to and to change the location to anywhere but the windows default and not to the Desktop as that location is in your user account folder as well, preferably on another partition or hard drive if you have one.
If you only have a single partition then create a folder on C:, call it Saved files or similar, then create folders inside that for your documents, photos, music and videos or anything else.
That way if the windows OS fails for some reason and you cant boot into windows you can still access all your data if you use that drive in another pc.
Hope that you can follow that ok David and that you may benefit from it in the future