The idea is that your website is made up of content. 'Content Types' define what your content is. E.g. It defines what an 'Article' is, what a 'Page' is and what a 'Blog' is. I.e. It defines 'types' of content by defining the fields each content type has. Several default content types are available after installing, but you can edit them or add more via the 'Content Types' tab in your control panel.
To add a new 'Article' or 'Page', etc. Navigate to the 'Content' tab where there are options to create a new piece of content for all your defined Content Types. E.g. Create a new 'Article' by going to 'Content' > 'Create Article'. You can manage your existing existing content by navigating to 'Content' > 'View Content'.
'Lists/Menus' control how your content is displayed to uses. When created each piece of content already has its own page, but website visitors need a way to access these pages and the 'Lists/Menus' generate the links for them to do so. These lists can be placed onto your 'Site Layout' page.
The other blocks on the Site Layout page are for once-off content that you do not need a separate page for, e.g. An announcement on your website, or a small blurb on your home page.
More information can be found in the user guide which is available in your client area and also downloadable here: http://www.interspire.com/websitepublisher/documentation.php
