How can I tighten the chain on my bike?

To tighten the chain on your bike, first locate the rear wheel axle nuts or quick release lever. Loosen them slightly to create some slack in the chain. Then, adjust the tension of the chain by moving the rear wheel back slightly. Make sure the chain is straight and not too tight or too loose. Finally, tighten the rear wheel axle nuts or quick release lever securely. Check the chain tension by spinning the pedals to ensure it is properly tightened.