Adding an image to the top of your module page can improve the look of the page and make it more appealing. There are a number of websites that provide free to use images and in the screencast below, the Pexels website has been used. When choosing an image for a page header you also need to ensure that the size of the image is suitable. If you have a standard size image, you can always open it in MS Paint (free Windows software) or similar free software, select the area of the image you want to use and crop, but it is much easier to just choose an appropriately sized image. The Pexels website allows you to enter the dimensions of the image you want prior to download so no editing is required which is ideal.
Watch the screencast to see how an image is downloaded from Pexels and added as a page header on a LearningSpace module page: