The first thing you need to do is grab your car jack, tire iron and spare tire. All of these tools come stock with any car and are locate in the trunk of your car or if it is a truck under the trunk lining or behind the seat trucks usually carry the spare tire under the truck bed.
Next take the carjack and position it under the axle of the flat tire. Try to be on flat solid ground to make this easier. Twist the eye loop in the jack to raise the jack. Raise the car jack until it is tight up against the car axle.
Some cars and trucks come with hub cap coverings. The lug nuts are behind the hubcaps Take a screw driver and pry the hub cap of to access the lug nuts. Take the tire iron and unscrew all of the lug nuts, do not completely take the lug nuts off, just get them loose.
Go back to the jack and raise the car up until your flat tire is about an inch off the ground. Unscrew the rest of the lug nuts and pull the tire off. You may have to persuade the tire off with some jiggling.
Now that the flat tire is off, put your spare tire on by lining up the lug nut threads. Now that you are in line, slip the spare tire on and screw on the lug nuts. Hand tighten the lug nuts until they are snug.
Lower the car by turning the jack the opposite way when you raised it. Use your tire iron and tighten all the lug nuts. It is very important that you tighten the lug nuts that are opposite of one each other. Make your way around the tire until all of the lug nuts are tight. Use your foot and body weight to stand on the tire iron to get the lug nuts tight. And you are done now you can change a car tire.