Here are the steps you can follow to change a car tire:

Park your car on a level surface, away from traffic and in a location where you have plenty of room to work. Make sure to engage the emergency brake and put the car in park (for an automatic transmission) or first gear (for a manual transmission).

Locate the spare tire, jack, and lug wrench. These are usually found in the trunk of the car or under the floor of the trunk.

Remove the hubcap or wheel cover from the flat tire, if necessary. Use the lug wrench to loosen, but not remove, the lug nuts on the flat tire. It's important to do this before jacking up the car as the weight of the car will help keep the tire in place while you work.

Consult your car's owner's manual to locate the proper jacking points for your car. These are the points on the car's frame that are specifically designed to bear the weight of the car when it is jacked up. Once you have located the proper jacking points, use the jack to lift the car until the flat tire is off the ground.

Fully remove the lug nuts and take the flat tire off the car. Set it aside.

Take the spare tire and align the holes with the lug bolts on the car. Make sure the tire is facing the right direction (the tread should be facing down).

Hand-tighten the lug nuts onto the lug bolts as far as you can.

Lower the car back down to the ground using the jack.

Use the lug wrench to fully tighten the lug nuts. It's important to make sure they are tightened properly, as the spare tire is not designed for long-term use and may not be able to withstand the same speeds and forces as a regular tire.

Replace the hubcap or wheel cover, if necessary.

Double-check that all the lug nuts are tightened properly and that the spare tire is secure.