How to add a new ResourceProducer in the Mod Editor?

[GaryP]

Hello all.
Can someone please tell me to how to add a new ResourceProducer or a new Resource Consumption section in the BuildingTemplate?
Do I have to open the code in Notepad++?

I've tried right clicking on the top of the template, looking in the menus. I just opened this yesterday and I'm looking for any bits on information.

I noticed the Build Menu Icon points to a tga. I'd like to use one of the in game ones. Where do I find them?
I'm thinking I may have to unpack something.
Long time modder and really green on this.

Thanks!!