The first thing you need to do is find a place with an air pump like at a gas station, you can also buy air pumps for around $30. You then need to locate where exactly the hole is. If it looks small enough to patch then buy a repair kit for the tire from a gas station or auto shop store and follow the instructions on the package to patch the tire. If it’s flat and you don’t want to drive, check and see if there is a car jack to lift your car to change the tire to the spare. If you don’t have a car jack in your car you should get one. You also need a tire iron to get the lug nuts off of the tires. There are plenty of youtube videos you can find to change a tire. If you don’t have those then you’re out of luck and would have to call a tow truck