There are 2 ways you can add/replace background images on the SquareOne homepage.
1. You can edit your css and replace the images with your own.
2. you can use the WordPress background uploader to automatically upload images without needing to use css* …..Although, the very first image of the SquareOne theme demo needs to be adjusted from your css since it is not a widget. We can help you change this if you need to (It’s easy). The first image is located around line 1815 in your style.css file.
To access the background uploader (from the WP admin), go to “Appearance“, then go to “Customizer” (from the dropdown menu) and on that page you’ll see “Background Images“. That’s where you can upload the images and they’ll show up on your homepage. You can see a preview of what it will look like before you publish.