iHeroFR

I'm very new to this whole process, could you help figure out how to do this?

Basically, I made a 2D texture that I want to display in the inventory. I want the item to (when placed) display as a block in the world. I've tried just redirecting the model path to the texture path but that results in the texture being mapped onto a three sided block with transparency. I've also tried adding a new path in the BlockItem of the block but that just killed the texture and resulted in the black/purple box. How do I display a block as a texture and not as a 3D block in the inventory?