Carefully hook a jumper wire to the signal connector on the starter solenoid. Put the car in neutral ( or park if it's an automatic ) with the parking brake on.
Connect a pair of jumper cables to the battery.
Connect the jumper wire from the starter solenoid to the (+) jumper cable.
Does it crank?
Incase you're wondering, the purpose of the jumper cables is so that you don't cause a spark near the battery. That can cause battery explosions in certain situations.