How do I make a 2D texture in the GUI for a 3D model?

Hi, I want to make my 3D object have a 2D texture in the GUI. I have not done anything else, can you please help me?

Here's the code I'm using now:
{
 "parent": "beautifulworld:custom/zenith",
 "textures": {
   "0": "beautifulworld:blocks/texture",
   "1": "beautifulworld:blocks/texture2",
   "particle": "beautifulworld:items/zenith"
 },
 "parent": "item/generated",
 "textures": {
   "layer0": "beautifulworld:items/zenith"
 },
 "display": {
   "gui": {
     "rotation": [ 0, 0, 0 ],
     "translation": [ 0, 0, 0 ],
     "scale": [ 0.5, 0.5, 0.5 ]
   }
 }
}

Here are the links to other questions with the form I've been building off of:
1) https://mcreator.net/forum/29652/2d-sprite-3d-model
2) https://mcreator.net/comment/229161#comment-229161
(DeepL translate)