Emacs commands are notated with C-x and M-x, where C is the control key, and M is the alt key. So, C-x means hold down control and tap x. C-x C-v means hold down on control and tap x, then tap v while still holding control down. C-x k means hold down on control, tap x, let go of control, then hit k.
Files:
| To open a file: C-x C-f | |
| To save a file: C-x C-s | |
| To close a file: C-x k | |
| To switch to split windows: C-x 2 | |
| To switch to one big window: C-x 1 |
Java:
| To compile: C-c C-v C-c | |
| To run: C-c C-v C-r |
The rest of the commands can be found both in the Emacs help - just go into "Browse Manuals with Info" under the help menu. JDE java commands can be found in the JDE user's guide (in your JDE directory).