How to use Vi editor on MacOS X

For my own sake, I put this note only for the most common case.

[shell]
1. %vi filename ------------ to open the file on vi

[vi]
2. i --------------------------- to change mode editable
3. arrow key to navigate the pointer
4. type to edit
5. Esc ----------------------- to exit edit mode
6. :wq ---------------------- to save data and quit

Done.
:-)