Generate your key,
zip and send the 'sender' subdirectory to the person doing the sending.
Instructions are provided.
you keep the 'receiver' subdirectory.
To encrypt a file, drag and drop
onto encrypt.bat
To decrypt a file, drag and drop onto decrypt.bat
READMEs are there to help.
For readers with Unix or Linux, you probably have openssl already. Take a peek inside the .bat files for some hints on usage.