In "World of Warcraft," copper is the earliest ore that players with the mining profession can pick and smelt. As the introductory material for the profession, copper is both plentiful and easy to work with, requiring only a mining skill of 1 to make bars. The only other requirement is that you find a forge to smelt down the ore into bars.
Smelting Copper Bars
You gain the ability to smelt copper ore into copper bars as soon as you pick up the mining skill from a trainer. Unlike many later metals, copper has a one-to-one ore-to-bar ratio, so a single bar only requires a single ore. Once you have copper ore and are next to a forge, open the professions menu using the "K" key, select "Smelting" and select "Smelt Copper" from the list. Clicking "Create" will create a single bar, or multiple bars if you enter a number in the field next to it. Clicking "Create All" will begin smelting all copper ore in your inventory or bank until you cancel the spell by pressing "Esc" or moving, or you run out of ore.
Locating a Forge
All racial capitals have a forge, as do many smaller settlements. The easiest way to find a forge is to find a blacksmithing or mining trainer -- they are almost always by a forge and an anvil. Ask a guard in capital cities for directions to these trainers, and you'll find your way to a forge. Alternatively, you can smelt from anywhere if you have a Thermal Anvil.