Changing your Homepage Picture
To change your website picture, hover your mouse over the WEBSITE tab then click on the PAGES sub-tab. Click on the "edit" button next to the Home section.
Then scroll down and click on the "edit" button next to Picture With Overlay Text widget. Under the current picture mark the check-box that says remove and click save at the bottom. Then click on the edit button again and it will allow you to upload your own picture.