I am using Magix Photostory Deluxe 2019 Version 19.0.2.46 (UDP3). Is there a way to add a video background and if so, can you send me a link to a tutorial of how to do it or instruct me how to do it. I am suing Windows 10 Version 1809 on a Dell Laptop Inspiron 7786.
Assuming you mean you want a background video for you slideshow, then if you are working in Storyboard mode you need to switch to working in Timeline mode.
In timeline mode, the background video must go on track 1, if there are objects on track 1 and lower tracks these must be moved down one track to accommodate the background video.
If it is a disc menu background you want to change see the video below, I am using an existing Magix video background in the example below, you can use your own provided it is a supported video format.