This image is a standard image I typically include on every community’s home page. I use the bottom-of-the-page WYSIWYG content area to do it. The width of the image is 750 pixels.
Below, I’ve used the single image content section. I’ve added the same image and selected the “content area” radio button. You can see that it’s left aligned compared with the centered image above. I’ve also added a vertical mobile version.