Switch -P[pwd] - set password
Set a password <pwd> to encrypt files during archiving or to decrypt during extracting. The password is case-sensitive. If you omit the password in the command line, you will be prompted to enter it.
In the shell mode a password may be entered through Enter default password dialog or in the Archive name and parameters dialog.
add the contents of the folder "games" to the archive "secret", using the password ZaBaToAd
WinRAR a -pZaBaToAd -r secret games\*.*