The commands are issued by holding down the Control key and hitting the associated key. The capitol C represents holding down the control key. So, if you saw, "C-x", that would represent holding down the control key and taping "x". If you have "C-x d". That would represent holding down the control key, then taping x, you'd then hit, "d" without the control key being held down.
Of course, one of the most important commands is how to exit emacs. This is "C-x C-c".
Other helpful commands are:
C-q Quit emacs (answer the prompts about saving your file).
C-x s y Save your file.
When you log into Apollo III using the terminal program, it may be best to set your terminal emulation to vt100. Most programs will have an options tab or menu bar at the top of the screen set this feature.
You should also look for the option for setting the arrow keys to function as arrow keys to have proper control of the cursor movement.
Finally, make sure that the screen is stretched for the 80X24 mode to insure proper display.