How can I turn copper ores to copper bars?

I want to make a Door but I need 2 Copper Bars to do so.

I have some Copper Ores but I'm not sure how to turn them into Copper Bars.

How can I turn Copper Ores into Copper Bars?

To convert Copper Ores into Copper Bars, you need a Furnace.

You need a workbench to make a Furnace. You can craft a furnace in the Crafting Stations and Furniture tab of the Crafting Menu for 8 Wood Logs. You can craft a Furnace in the same tab, which costs 10 Stone Blocks and 3 Wood Logs.

After you have a Furnace (and have placed it and crafting through it), you can open the Blocks & Ingredients tab of the crafting menu and craft a Copper Bar for 4 Copper Ores and 2 Coals.