Here are the steps to fix a running toilet:

1. Remove the lid from the toilet tank and place it in a safe location where it won't get damaged.

2. Take a look inside the tank and identify the flapper valve. This is the rubber or plastic piece that covers the hole at the bottom of the tank.

3. Check the chain that connects the flapper valve to the flush handle. Make sure it is not too loose or too tight. If it's too loose, the flapper won't close completely, causing water to continue running into the bowl. If it's too tight, it can prevent the flapper from opening fully and cause a weak flush.

4. If the chain is too loose, adjust it to the proper length by moving the hook on the chain to a higher or lower hole on the flush handle.

5. If the chain is already at the right length, check the flapper valve itself. If it appears to be worn or damaged, it may need to be replaced.

6. If the flapper valve looks fine, check the water level in the tank. It should be about an inch below the top of the overflow tube. If it's too high, the excess water will constantly flow into the bowl, causing the toilet to run.

7. If the water level is too high, adjust the float. The float is a plastic ball or cylinder that regulates the water level in the tank. You can adjust it by turning the screw on top of the fill valve. Turn it clockwise to lower the water level and counterclockwise to raise it.

8. Once you've made the necessary adjustments, turn the water supply back on and let the tank fill up. Flush the toilet a few times to make sure it's working properly and there are no more leaks or running water.

That's it! Hopefully, these steps will help you fix your running toilet. If you have any further questions or concerns, please don't hesitate to ask.