How do I properly edit and save a file using Emacs from the terminal?

I'm new to Emacs and trying to edit a file from the terminal on a Linux system. I ran the following command: emacs /root/quote_dora It opens Emacs, but I'm confused about how to enter text, save the file, and exit properly. Can someone explain the basic steps to:

Enter editing mode

Save changes to the file

Exit Emacs safely

Also, how can I verify that the changes I made were actually saved?

Thanks in advance!