WinRAR lets you encrypt your archive with a 128 bit key. To guarantee optimum security, we recommend using passwords with more than 8 characters in length and to combine letters and numbers in the password.
Go to the file you want to put password on right click and go to add Archive and box below shold come up.
In the dialog box choose the option "Set password"
Enter your password.
If you choose the option "Show password", you'll be able to read the password and it will not be marked with asterisks.
The option "Encrypt filenames"; will show a password prompt right when the archive is opened, without showing the files it contains.
Or see the video on youtube
http://www.youtube.com/watch?v=l93Wm4XggT0
