Editing Address Details on the Contact Us Page

Login as Admin with Username/Password
Move the cursor to 'Site Building' which is the second menu item on the 'Admin Bar'
This results in the drop down menu having different Menu items
Click on Contact form that appears in the drop down menu
Click on the 'Settings' button which is the third button of the three buttons namely 'Add', 'Add Category' and 'settings'
Make relevant changes such as editing the default message and placing address details in the 'Additional Information' block.
Click on 'Save Configuration' to save the edited information

You can directly go to that page by clicking here…http://www.yoursite.com/admin/build/contact/settings