I know nothing about all this encryption stuff but, assuming you are running XP...
1. First compress your folder. Rightclick the folder you wish to protect and sent to 'compressed (zipped) folder'.
2. Double click 'My Computer' and locate the folder through the directory.
3. Double click the compressed folder and on the File menu click 'add a password'.
All the items in the folder should now be password protected.
To undo, rightclick the folder and click 'extract all', next, press 'password' and enter password, next. All items should now be available for unprotected viewing. Note: Compressed protected folders can still be deleted by anyone!
Hope this is of some help.