How to Publish Your iLife '11 iWeb Site
Your iWeb site doesn't exist as a true website until you publish it on the World Wide Web. Also, the changes you make to pages in iWeb after publishing your site don't take effect on your site until you publish the site again with iLife.
To publish a site, select the site in the Sidebar, adjust the site's publishing settings, and click the Publish Site button on the toolbar. (You can also choose File→Publish Entire Site.) To publish only the changed pages of a site, choose File→Publish Site Changes. Publishing only the changes is faster than publishing your entire site; however, you need to publish your entire site again if its navigation menu changed (because of rearranging or renaming or deleting pages).
Sites and pages that have been published are blue in the iWeb Sidebar, and sites and pages that have changed (even slightly) are red so that you can see whether a site needs to be published.
If you have a MobileMe subscription, you can publish one or more sites using MobileMe.
You can also publish one or more sites to a third-party hosting service using FTP (File Transfer Protocol), which is built into iWeb, whether or not you have a MobileMe subscription. Most people use this option to publish into their own domains that are already set up for them.
As a backup, or to use your Mac as a web server for your site, you can publish one or more sites to a folder. You can then turn on web sharing or use web server software on your Mac.
If you create more than one site in iWeb, you can publish each one separately, to whichever host you want — some to MobileMe and others to a different hosting service using FTP.