How to set password in existing winrar archive?

Hi ,

I have a winrar file and i want to set password in that , I googled this but I find the way to set password while you are making NEW WINRAR ARCHIVE,

but i have already made an archive without password and now i want to add password in that..

I tried to set password in the archive from file menu of winrar but it doesn't set password, it makes no changes in archive.

thanks

Create the archive again.. :|