If you notice water pooling around the base of your toilet, it is important to act quickly to prevent water damage to your bathroom. Here are some steps you can take to troubleshoot and fix the issue:

1. Shut off the water supply: The first step in addressing a leaking toilet is to shut off the water supply. The water supply valve is usually located behind the toilet, close to the floor. Turn the valve clockwise to shut off the water supply.

2. Check the toilet tank: Once the water supply is shut off, you can begin to troubleshoot the issue. Check for any cracks or damage in the toilet tank. Also, make sure the water level in the tank is not too high. If the water level is too high, adjust the water level using the fill valve.

3. Check the water supply line: A leaky water supply line can cause water to pool around the base of the toilet. Check for any leaks or damage in the water supply line. If you notice any damage or leaks, turn off the water supply and replace the supply line.

4. Check the wax ring: The wax ring is located between the toilet and the flange and seals the toilet to the drain. If the wax ring is damaged or broken, it can cause water to leak from the base of the toilet.

If you are unsure how to shut off the water supply line, here are some steps you can take:

1. Locate the water supply valve: The water supply valve is usually located behind the toilet, close to the floor.

2. Turn the valve clockwise: To shut off the water supply, turn the valve clockwise until it stops turning.

3. Check the water supply is off: To ensure the water supply is off, flush the toilet and check if water is still flowing into the tank.

These are some basic steps that you can take if your toilet is leaking and how to shut off the water supply line. If you are still unsure or uncomfortable with handling the issue, it may be necessary to contact a professional for further assistance.