Accessing an existing SkyVault site is easy.
You can search for sites using the Site Finder, the search box on the SkyVault toolbar, or you might receive an email notification that you've been added to a site.
If you see a link to a site anywhere in SkyVault, just click the link to have a look.
You can see all the sites you're a member of by clicking Sites then My Sites on the SkyVault toolbar.