You can't add your own domain to jAlbum. Your jalbum.net site address can be used only for hosting jAlbum albums - it is not a general-purpose web host.
You can create albums and host them here, then put links to them on your own page, or display them in iframes on your own page.
(The OP has a commercial domain that would not work on jalbum.net - loads of server-side stuff going on.)
You can point your domain to your jalbum address (xuanbinhco.jalbum.net) by adding a cname in your dns, and then add the domain to a list on your Settings page. That way you can access your albums stored on your jalbum storage using your own domain.
This user's domain (I deleted the link, suspecting backlinking) contains a blog, a shopping cart, etc., etc., all things that wouldn't be possible on jalbum.net. Lots of PHP and databases.