Gpg4win might be your best bet. Assemetric encryption is already a pretty complicated topic and would be pretty hard to dumb down any further. Still, it looks as if this particular software at least provides a GUI to navigate around in as opposed other command line tools like GnuPG.
The only downside I can see is they throw in a few extra added features that you may not use.
On the other side, if you don't require assemetric encryption, you can always use a WinZIP or WinRAR to encrypt as long as you use a strong password (at least 8 character, using numbers, upper, lower, special characters, etc)