1. Gather necessary tools and materials: Before starting the process of changing a car battery, make sure you have the necessary tools such as socket wrenches, terminal puller or pliers, gloves, safety goggles, and a new car battery.

2. Park your car on level ground and engage the parking brake: To ensure safety while working on your vehicle, park it on level ground, turn off the engine and set the parking brake.

3. Open the hood: Pull the hood release lever located inside your vehicle and then open the hood by lifting it up.

4. Locate the battery: Find the car battery under the hood. It is usually rectangular in shape, with cables connected to two terminals (positive and negative) on top.

5. Disconnect the negative (black) cable first: Using a socket wrench (or pliers if unavailable), loosen the nut holding the negative (black) cable onto its terminal. Once loosened, detach it from the terminal by wiggling it side to side.

6. Disconnect the positive (red) cable: Follow the same process as step 5 but with the positive (red) cable.

7. Remove any brackets or hold-down clamps securing the battery: Many vehicles have brackets or clamps holding the battery in place. Use a socket wrench or other appropriate tool to remove them.

8. Lift out the old battery: Wearing gloves and goggles to protect yourself from corrosive battery acid, gently lift out the old battery. Dispose of it properly at a recycling center or automotive store that accepts used batteries.

9. Clean the terminals and tray: If there is any corrosion build-up around terminals or on battery tray, use a mixture of baking soda and water to clean them off thoroughly using an old toothbrush.

10. Install your new car battery: With clean hands, lower your new car battery onto its tray in the battery compartment, ensuring that its terminals are facing the same direction as the old one.

11. Reattach the cables and brackets: Reattach any brackets or hold-down clamps to secure the battery. Next, reconnect the cables, starting with the positive (red) cable and then the negative (black) cable. Tighten the nuts securely.

12. Close the hood and start your vehicle: After completing all steps, close your car’s hood. Now, start your vehicle to ensure that it is operating properly with the new battery installed.

After successfully performing these 12 steps, you will have changed your car battery! Always remember to recycle your old battery responsibly and perform routine maintenance on your vehicle to keep it in optimal condition.