ROM (the first one on the top left) is for the ore that your mining ship brings. Right next to it is import, i.e. everything you buy in terms of ore. To the right, A and B, with later upgrades also C to G, are for storing ore. Initially you only have the blast furnace underneath. This always needs coal and the corresponding ore, i.e. iron, nickel or copper, with upgrae for sand processing also glass, titanium and something else that I don't remember at the moment. Sand processing is the gear symbol to the left of the blast furnace. To the right of the blast furnace, with an upgrade, is the arc furnace, which no longer needs coal. On the far right is the last processing unit for gold, diamonds, quartz and carbon. Gold, diamonds and carbon always require a corresponding ore , which you can buy or get with the mining ship. Quartz, titanium, and the stuff I don't remember always need sand, which is then broken down into its components. Finally we have export and waste products, this should actually be self-explanatory^^ Hope this helps, even though the response came quite late.