#save changes in vi editor

by press i you can `Insert` anything. After finshing changes then press :(colon)
and type wq!

syntex : wq!

Explanation : The ex mode is an extension of command mode. To get into it, 
press Esc and then : (the colon). 
The cursor will go to the bottom of the screen at a colon prompt. 
Write your file by entering :w and quit by entering :q. 
You can combine these to save and exit by entering :wq. 
However, if you're finished with your file, it's generally more convenient to type Shift-z-z from command mode.