To edit the footer file with your information follow these instructions:
Go to "File tab on the main window.
Select "open" and browse to and open "main.dwt".
At the very bottom of the page in design view or source code you will see the footer. Just type the new information, overwriting the current and save it..
You will then get a popup saying there are # of pages connected to the main dwt and do you want them updated. Select yes and all you page are now up to date and reflect your new footer information.