Robert,
Like Francis mentioned use the search feature on the green menu bar at the top of the screen. Come up with questions on what you don't understand or need clarification on.
Coke is what is left from the coal when the volatiles like sulfur have burned off. It burns clean and hot. You save some of this from each fire to have available the next time you forge.
As for fluxes, well, you'll have to try for yourself to tell that one. Many of us just use Borax to start with because it is cheap and easy to get. I have used one or two other types and saw no real benefit but my experience is pretty limited.
Send me a Private message if you want.