Emacs Exiting and Help

To close out of emacs

C-x C-c

If you have any open buffers, it will ask you to save it before closing out of emacs.

Confused?

C-h C-h : help menu

Undo

C-x u

As you can see Emacs has more moving parts, so the learning curve is a little steeper. In exchange though, you get a very powerful text editor.