The procedure is explained below:
other sources:
http://www.wikihow.com/Add-a-Password-to-a-RAR-File
https://www.youtube.com/watch?v=9DFbu487C4Y
[*]Select a file.
[*]Right-click > Add to Archive.
[*]Winrar will open.
[*]Click on the Advanced tab.
[*]At bottom right of the window, click on Password.
[*]Define your password and save your settings.
other sources:
http://www.wikihow.com/Add-a-Password-to-a-RAR-File
https://www.youtube.com/watch?v=9DFbu487C4Y