If you have chosen to play on easy difficulty a coal vein and extractor are provided for you, otherwise you'll need to search for fuel. If you are extremely lucky, the impact crater will have exposed a coal vein. But the more dependible source of initial fuel are the trees around the crater. Dig up the trunks and collect them. Now head towards the hub, interact with it ('e') and press 'add resources'. This will start burning one of your logs. You will have to manually add more fuel to it, until you have to resources to automate this process.