You can use the Paint Bucket tool in order to add a white background to your creations. Also, you can press the Ctrl + F key combination to open the Backgrounds Settings window. Usually, the background of the models is set as transparent in the PNG format. You can use a photo editor to resave the file as JPEG. This format doesn't support transparency and converts any transparent pixel to white.
You can use the Paint Bucket tool in order to add a white background to your creations. Also, you can press the Ctrl + F key combination to open the Backgrounds Settings window. Usually, the background of the models is set as transparent in the PNG format. You can use a photo editor to resave the file as JPEG. This format doesn't support transparency and converts any transparent pixel to white.