If all you wish to do is use one of the pre-packaged options, click on the Application Icon up in the top left of the Inventor window (the big, ugly, mustard colored I), and go way down to the bottom of the Application Options that appear and you will see a little box titled ‘Options’. Click on it to bring up the Application Options window that contains the application variables that Autodesk deems you worthy of futzing with. The color schemes haven’t changed since I started using the program, so I generally make my own images to use as a background which will be explained more below. If you just want to change the stock settings, click on the ‘Colors’ tab, then chose the color from the ‘Color scheme’ box, and whether you want a solid color or a gradient from the ‘Background’ drop-down.
If you want an image, change the ‘Background’ setting to ‘Background Image’ and select from one of the stock images by clicking the little folder icon next to the ‘File name;’ box, which is just below the ‘Background’ drop-down you just used. Hit apply to see the changes. If you like it, click close and you have it. Its always a good idea to close Inventor after making changes to the Applications Options because the next crash will loose the options unless the program was shut down in-between.
If you have downloaded the Background Image from one of the tutorials, save it to C:\Users\Public\Documents\Autodesk\Inventor 2016\Backgrounds and your own backgrounds will show up when you click on the file search icon as is shown above. To customize, just make your own .png backgrounds at 1276 x 922 and save them in this same folder.