Editing

i - insert
a - append

Navigating

j - move down
k - move up
l - move right
h - move left

Exiting

:qa - Close all files
:qa! - Close all files and abandon changes
:w - Save
:wq - Save and close file
:x - Save and close file
:q - Close file
:q! - Close file and abandon changes
ZZ - Save and quit
ZQ - Quit without checking changes