QUOTE(99rays @ Aug 13 2009, 08:38 AM)

inorder to save back on his server do i need his ftp login credentials
To save it manually, using FTP might be the simplest solution.
To do it automatically you might use a server-side script on his server that can write the new content (with PHP, see
file_put_contents). You also need some kind of password protection, like HTTP authentication, otherwise anyone could make changes on his pages.
You also need to get the edited HTML from the editor on your server to his server script. If you put the finished HTML code in a hidden form field on your server, you might submit this form to his server-side script, which in turn saves the HTML on his server. Not sure how to handle the PW protection in that case, though: maybe you just submit the form, the PW login prompt shows up, and after entering the PW his server-side script runs.
Possibly it would be more intuitive if the PW login prompt was shown before the user began editing. One way to do that would be that the user first went to a login page on his own server, entered the PW on that page's prompt, and after that continued to the editor on your server.