How do I back up programs off my boss' computer? (no IT dept)

I think I know just enough about computers to be dangerous, as they say!

My Boss’s computer has been crashing. Before it goes out all the way, we want to back up his programs.

I have been researching online and asking people—how do I back up programs?

I have a flash drive for documents, but isn’t it just for documents, spreadsheets and the like? I need to back up programs.

I have attached to my computer a NexStar3. I think this does what I’ve been trying to research, but I don’t know. I was told to back up files and to run the NexStar3 once a month.

When I turn on the NexStar3 there are several things that come up, naming my computer, the boss’, a co-workers and another machine.

Should I just unplug it from my PC and plug into his to back up his programs?

Not sure if we have discs for all programs. Will I need them in addition to the NexStar3 or will we be able to salvage his computer using the NexStar3?

Thank you!