To open iWeb on the Apple computer, click on the iWeb icon in the dock. If the icon is not there, go to Spotlight (command + space), and type in iWeb.
Editing in iWeb
When iWeb opens up, it should automatically bring up the CRIPT Anatatorium project.
The pages will be on the left in a sidebar. Click on the pages you wish to edit and make changes.
Make sure you save every time you make a change.