This is the first page.
Mark, if you click on the title ("Home") you'll get to a page where you can click on the "Edit" tab. Click on that and you should be able to edit the page body easily. If you are comfortable with editing regular HTML, you can click the "disable rich-text" link to turn off the fancy editor.
You can click the "Preview" button at the bottom of the page to see what it would look like without committing your changes. When you are satisfied, click the "Submit" button and it will save your changes.
The links on the page with the small triangles are expandable sections. Click on one to expand or contract the section. Some of these might have stuff of interest. For example, under the "Publishing options" section is a checkbox called "Promoted to front page". On any page where that is checked, that will make a preview of the page show up on the site's front page.
