On the “Crimes” and “Nick a Car” page you select the job with the highest chance, fill in the code and press the “Go for it” button.
You should do these crimes now because after you have done a crime you need to get some energy again before you can do the same job again.
How do you do that? Simple: Just wait 90 seconds. Find something else to do while you wait...
After doing a regular crime you need to wait around 90 seconds and around 300 seconds before you can try to steal a car again.
If you managed to steal a car it will be in your “Garage” – take a look! You should sell it if it is worth more then $1,000 else you can keep it to make bullets from (once you are higher ranked).
The dangerous the crime, the higher the reward.