Log in to your site.  When you hover your mouse pointer over something that is editable, a box will appear around it to let you know it is editable.

If you want to see everything that is editable on the page, click the magnifying glass button next to the logout button in the bar at the top of your site.

You may also find some editable content by clicking the "Page Options" link at the left of the bar. This section consists of two tabs, "Edit" and "Optimize". "Edit" can contain some of the things you can edit on the page as well as some extra content like the title of the page which shows up in navigation and/or the email address to send contact form information to on the contact page.

"Optimize" contains the URL for the page (if editable) and the META information for the page.