Hey, thanks! That sounds like a fun project :)
What you have to do is to prepare an image that contains both the number and the eye. So, in your case, you'd probably want to create an image for each face (each number) of the dice you intend to make.
Also, I heavily encourage you to use SVGs instead of bitmaps, the result will most likely be much sharper. Bitmaps are raster images, that the app needs to convert to vector graphics. It's better to just use a vector graphics format (like SVG) to maintain high fidelity of images.