B4W Calling assets from updatable dynamic library?

I have read that this can obviously be done with the JSON callback logic node.
I'm wondering if anyone could point me to a very basic learner's version of how to populate new instances of objects from a database?
these assets are mostly square images all the same size,
and a myriad of complex 3D objects.
I'm looking fore scaleability, so i think starting this way would be wise.
thanks!