How to Download These Backgrounds
To start using the background for your favorite team, go to their website. See if there are free background downloads available. Teams like Duke University and Wake Forest both have free background downloads available. If they do have free background downloads, then select the background that you would like to use. Many of the sites have different resolutions for the background. You should probably select the highest resolution as the higher the resolution is, the better the final picture will look.
Once you click on it, this should take you to a larger preview image. Right-click on the image and select save as. Give your image a name, and then save it to your desired location.
There are also generic basketball wallpapers available from several different third-party websites, which you may use without having to pay for a license. Sites like FanImages.com and BaskeWallpapers.com could be a good place to start, but you will have to do a lot of research to find an appropriate background on these sites. These backgrounds tend to be very busy, and, you will have to do a lot of searching if you are looking for one particular team. But, most of these backgrounds are free as well, which means that you can always change them up to fit your needs.
You should only use backgrounds and photos that you have permission to use. Do not just copy and paste photos from different websites, or it may be infringing on someone else's image rights.