Start by selecting Site Builder from the Administration>Site Management page.
From the Site drop down list, select Add Header Image to display the Header Image widget settings.
The recommended size of the header image is 1170 x 150 pixels width x height. If the image is not the correct size, you may find that it interferes with the look of the Home page in Site Builder.
To change the image size in Windows, use an accessory called Paint and then resize it in pixels. You can also crop the image to get a better fit.
To change the image size in a Mac environment, use Tools in Preview.
Click Browse to find the required image from your computer.
Select the file and click Open.
Click Save Header Image and wait for it to load onto the background.
Here is an example of the uploaded header image, which has used a number of images put together.