Emacs 6: Offical Tutorial Part 5

There are many C-x commands.  Here is a list of the ones you have learned:

        C-x C-f         Find file
        C-x C-s         Save file
        C-x s           Save some buffers
        C-x C-b         List buffers
        C-x b           Switch buffer
        C-x C-c         Quit Emacs
        C-x 1           Delete all but one window
        C-x u           Undo

>> Move the cursor to the blank line two lines below this one.
   Then type M-x repl s<Return>changed<Return>altered<Return>.

   Notice how this line has changed: you've replaced the word
   "changed" with "altered" wherever it occurred, after the
   initial position of the cursor.