Handy VIM cheatsheet!
IN COMMAND MODE (hit the escape key, friend!)
i -- insert text at the cursor
a -- append text after your cursor
R -- overwrite the characters that your cursor falls on
x -- delete the character your cursor is on
dd -- delete the line your cursor is on
Saving the file
ZZ -- saves the file!
Exiting without changing the file
:q! -- it's your Get Out of Jail Free Card!