Hello, looks like you just need to make an emissive mask texture to do this. It looks like you are just applying a solid color into the emissive channel.
You can make a texture similar to this:
When your mask texture is plugged into the emissive channel, the white portions will glow and the black will not. If you want to have color, you can just add a 3 vector color to the mask before you plug it into the emissive channel.