Add background image to shape?

Hi

I am able to draw / Drag and drop a sqaure to my canvas which was fairly straight forward

I have defined some properties for this via a merged dictionary in resources and the xaml code for the box is:

 
 

 
 
 //Removed some xaml to keep it short
 
 
   
   
      
   
 
     
 

However i would like to assign an image to the shape is this possible as i cannot seem to achieve this no matter what i do i seem to generate varying errors dependant on where and how i attempt to apply the image to the BoxItem.

Any ideas as this is defeating me at the moment.

Many thanks