In order to hotwire a car, you will need to cross the wires that lead to the ignition coil. The ignition coil is responsible for providing the spark that ignites the fuel in the engine, so by crossing the wires that lead to it, you can bypass the car's ignition system and get the engine to start. There are usually two wires that lead to the ignition coil - one is the primary wire, which carries the current from the battery, and the other is the secondary wire, which carries the current from the ignition switch. To hotwire the car, you will need to connect the two wires together.
If you are not sure which wires to cross, you can consult a diagram of the car's ignition system. Or, you can try crossing the wires and seeing if the engine starts. If it does, then you have found the right wires. If it doesn't, then you will need to try a different combination of wires.