Sporty supports the use of transparent images.
You may be trying to create an image that has transparent elements for the design of your website. If you image does not appear to be transparent, check the following things:
Is your image saved in a format that supports transparency? The most common file types supporting transparency are GIF and PNG. You will also need to make sure that transparency is enabled when you export your image from your image editor (e.g. Photoshop or Paint.net). Note that JPEG images do NOT support transparency.
Check that your image has a transparent background in your image editor. Your image editor may have a white background by default that you will need to clear before saving the image.