There is nothing wrong at all with having some white space on your web site. And you shouldn't need that you need to fill up every single piece of white space. But I think this space here in the right hand column is just a little bit too much for my liking. So I am going to add a module there.
I am going to go to my Extensions and Module Manager and going to click New and select a Custom HTML module so that I can place an image in there. I am going to give it a title so that I can find it again. But set that title to hidden as I wouldn't want that to be displayed. I need to select a position and I already know that the right hand column is Position-7. Then I can go to my Custom output. As I only want to put an image in here I can simply click on the image icon and then an upload an image that I've prepared already. Select it and Upload. Once its uploaded I can see a preview here to make sure its the correct image Click on the icon to insert it. I need to make sure that I fill in the correct alternate text and when I've done that I can scroll down and click on Insert to place the image inside the module. I can now click Save & Close.
If I return to my web site and refresh the page we can see that the image is there. Unfortunately its above my important button so I need to change the order of these modules. So if I return to my administrator we can change the order of modules exactly the same way as we did with some articles earlier. Let's filter this list by the position so we only show modules in Position-7.
If I click on this icon here I'm now able to do the ordering. So to move Long Right to the bottom place your cursor over the three dots click and drag and drop it at the bottom. Now that's done just go back to your web site and refresh the page to make sure. We can see that the button is now above the image.