Winrar is shareware. The trial is time & function-limited so encryption may be disabled. If this is the case, there's a very capable freeware zip/unzip program (that I use) called IZArc click here, which has a 256-bit encryption capability.
Also, if you need to lock away files/folders there's a free program, Cryptainer LE click here, which is well worth considering. G
NOTE: For all these programs do NOT forget the password(s) you set!
Highlight the files you wish to zip or rar. Rightclick "add to archive". Once you've selected parameters on the opening General Tab,click Advanced and you'll see the "Set Password" button halfway down on the right.