Modes, Commands and Help

In emacs there is a mode for each file type
(among other uses, there is also a doctor mode).

Each mode has its own commands and short-cut-keys.
Type "M-x" (M=Meta=Alt) then a command name.
You can use tab to complete or to get list of possible completions..
Use the command "describe-mode" for info of the mode of the current buffer.

Help:

C-h               Displays help window  
C-h C-h           Gives you help on help
M-x help          Displays help window (alternate method)  
C-h t             Shows the tutorial  
C-h a             Shows commands matching a string  
C-h i             Enters the Gnu Info documentation browser
A-x manual-entry  Manual-entry for string under cursor
A-x ispell-buffer Spell checker
A-x doctor        Doctor

Panic: When things run out of control try:

C-g       Runs the command keyboard-quit
C-_       Undo