Should be easiest just to create a new folder in Windows Explorer such as c:\killme and copy the DVRFlash.exe and the two bin files into that folder, then just start the DOS window and move to the killme folder and just run the .exe from that place.
If you are in another folder when you start the DOS folder, then just write
cd \killme
and you should be in the killme folder where you have copied the .exe and the two bin files. You can check that the files are in that folder when you are in the DOS window by typing
dir
you should then see a list of the files in that killme folder.