Smelting and smithing
1. Get ore
Mine rocks in runs: click a rock to walk up and mine it, with the best pickaxe you own. Copper ore and Tin ore make bronze; iron, coal and better ores come with Mining levels and harder zones. Ores are also sold at the Grand Exchange by Farid Morrisane.
2. Smelt bars
Every house has a clay furnace on the garden's west side. Walk up and press E, choose a bar and how many. One copper ore and one tin ore make a Bronze bar.
3. Smith
Smithing bars into weapons, armour, arrowheads and nails needs an anvil, built in a Workshop (Construction 15). The anvil needs Construction 10, Doric's Quest and 5 iron bars.