How to use images
Image Manager
Import the image into your model via the Image manager (Tools -> Image Manager...).
HTML View
Drag&drop an HTML view element onto your story board, have the URLs to the images ready for your application (ideally coming with your e.g. material master API) and fire the corresponding URL into the HTML View.
BI document
Use a similar approach as described in the following document:
How To... Integrate BI Document Store and SAP Analytics Applications