Has proven impossible for me so far. Repositioning, scaling, rotating works just by looking at their Inspector property names, and using that in code, but frame, frame coords, frame anything... let me not to tell you how many possible variations and combinations i'm through at this moment... just won't work, in fact any of them prevents the compiler finishing without an error.
I've chosen the simple Sprite node type as that has a normal map option, and i just overall want a tile map (done on my own, i want total control, not interested in the built-in tile editor) created off of a 2d Array containing the specific image IDs to each tile.
Please kindly let me know if i'm doing a screamingly stupid thing anywhere, because i just started using Godot last night.

I grayed out the frame line in the code so it runs, and this is the map so far. I darkened the tiles which should change according to the 2D Array if the frame line worked.

So how do i change the frame of each instanced sprite properly?