Using Background worker - Need help...

Right, I have a program that backups files from a source folder to a destination folder.

If I want to pop up a window to show a progress bar which code needs to go in the DoWork method within the Background Worker?

Which goes into the background worker:

A) The code to actually copy the files
B) The code that updates the progress bar
C) Both

I would imagine that it is A personally, as that will be done in the background?
Is it right to say that when using a background worker you are using a different "thread"??

So the code within the gui is the "MAIN" thread and the background worker is a secondary thread??

I don't want the actual code, just some guidance so I can figure out as much of it myself as possible.