Can't Put OBJ Custom Model For Block In 1.7.2

I am having a problem with my mod. I am trying to make a block that is a 3D Custom Cookies and Milk on a plate, but I turned the files from blockbench to OBJ and JSON none of those work. I turn it into a Blender file and another OBJ, but it keeps telling me when I put the file in that I need to put a custom model in. It makes no sense because it won't let me save anything I put in the custom models! It really is bugging me. So any help?