Im very new to SilverStripe and made some simple mistakes.
In order to user methods such as .URL etc with images you have to declare a new database table first using either $has_one or $has_many. Then add a tab. Then you will have a new tab where you can upload images in your CMS and use them at will. I guess I will need to use an enumerated type for more than one image.
Im using this to allow people to update background images in the CMS so I can have text overlayed over an image rather than static pictures!