How to make a new template in Gantry

I want to make a new template in Hydrogen/Gantry for a blog listing that shows posts tagged ‘featured’ as sticky posts at the top. The technique in twig to do this has been explained to me, but on a much more basic level I am at a loss to know how you even make a new template here. Web searches are surprisinly unhelpful, and the Gantry documentation as far as I can seem makes no mention of it. Is i just too obvious to document? I am not sure what I am missing.