7) Save the file and go into your item textures, located at: \AppData\Roaming\.minecraft\resourcepacks\RESOURCEPACK\assets\minecraft\textures\item
8) Here you will need to add the textures for the models. MAKE SURE that the texture is called the same as what you changed "layer0": "item/TEXTURE_1" to in the previous model, in this case the texture should be called TEXTURE_1.
9) Reload your resourcepack (F3+T)
That should be it, but I might've screwed up somewhere in the text, so do feel free to contact me if you need further help!