Your definitions are not right. "Greens" are often, but certainly not always, green in color. "Browns" are often, but certainly not always, brown in color.
You are right about "somebody's going to talk 'carbon' and 'nitrogen'." "Greens" contain nitrogen. "Browns" contain carbon. So composting is really a balance of those to key elements, nitrogen and carbon. The reason for this is the bacteria we rely on in composting feeds on nitrogen. Carbon is the building block of the compost. Carbon rich matter does not break down as fast, so it provides structure to the pile. If you just put nitrogen rich matter into a pile you would end up with something similar to a pile of sewage slime - not something you really want to mess with.
Now let's talk about what is "green" (rich in nitrogen) and what is "brown" (rich in carbon". Some common "greens" include manure, urine, and most fruit and vegetable scraps. Some common "browns" include wood (sticks and wood chips), straw, dry leaves (although fresh leaves are mostly "green"), aged/dried grass clippings (when it's more like straw or hay).
Generalizing it all:
"Greens" are: food, green plants, manure and urine
"Browns" are: woody things, paper and brown plant matter
Of course there's more to consider yet still in composting: ph (alkaline or acidic), phosphorous, potassium, calcium, moisture and more I'm sure. That said, start with the basic above and build a pile or fill a bin. The rest will come as you continue to learn.