This achievement is very easy and may be the first one you get.
To get this achievement simply look for a car which has its doors open then take cover at the front of the car and move towards the back 'shutting' the door. The achievement will pop shortly after.
If somehow you are still having trouble with a very simple achievement that a fish flopping around on the joystick could do then here is a 25 second video showing how to unlock it.