To change the background image in your design or template you may need to delete the existing background image. You can do this by clicking on the image and clicking delete on your keyboard or by clicking on the image and then choosing the delete icon on the tool bar.
Once you have deleted this image, you can then choose your new background image or upload your own using the Upload folder. To choose a new background image from the image gallery, select the Image item on the side menu bar. Using the search bar you can find images that suit your design.
Once you have chosen your image, click on it to add it to your canvas.
Now you need to order your layers so that the background image is at the back and all other items are overlayed onto it. To do this click on the layer icon on the right hand side panel and click on the icon (show icon v) to set the image as the back layer.