You can put a .htpasswd into your root folder of the FTP, and a .htaccess file into the folder you want to protect on the FTP along with everything in it. google "htpasswd" for a code generater to transtale your user/password the acces should look something like, AuthName "Restricted Area" AuthType Basic AuthUserFile…
I would never distribute a .zip - I would set up a private folder on your webspace. From there, I would password protect that folder and provide unique user/pass for each user you're giving access to, so you can "track" a leak and discourage sharing it. This also let's you remove the content - once you've e-mailed a .zip…