Your iWeb sites are stored in what is called an iWeb Domain file (.sites2 or .sites file type) which by default is stored in your Library–>Application Support–>iWeb–>Domain
However, in Lion (Mac OS X 10.7) & Mountain Lion (Mac OS X 10.8) the Library was hidden from the user. Here is how to access it again:
Click on the desktop, then use the GO menu then, hold the “option” key on the keyboard.
I had split my original iWeb domain a few years ago & had got into the habit of creating a new domain for each site I design. However, after updating to OS X Lion “10.7” & later “10.8” no matter which domain I double clicked on they all seem to just open the last site I was working on in Snow Leopard “10.6.8”
If you have more than 1 iWeb domain file you will need to use the iWeb Multi-domain tool.
http://jeffnitschke.com/Multi_Domain_iWeb.zip
And if you haven’t got a 3rd party web host yet I would suggest IX Web hosting.
I have been using IX Web hosting for several years with little to no problems “usually the problem was something I did” and they have been quick to solve any issue I have come across. They have plans that start at $3.95 a mo (USD) and their customer service is top notch.
http://jeffnitschke.com/IXWebHosting.html
http://jeffnitschke.com/wordpress/2012/06/how-do-i-move-my-mobileme-site-ix-web- hosting-blog/
Jeff, there is an easy way to not use a 3-rd party App in Mountain Lion… When you open Library–>Application Support–>iWeb you see your Domains. If you give each one a name ( Domain Vacation, Domain Real Estate,etc and leave only the one you want to open as Domain it will open in IWeb. To open another one – rename again. The point is that IWeb always opens Domain and nothing else… If you add to Domain name and nothing is just plain Domain, then IWeb opens a new, clean copy (I have .sites 2 extension hidden so I don’t even mention that…)