Hi, first I am a total novis so bear with me.
I will put my car in a round picture with the US flag as a background in the ring. I will see the flag trough the car only in the ring. The car sharp outside the ring bouth in front and back. Only transparant in the ring so I can se the flag.
Two ideas:
Keep the size and position of the two car images identical. Then put the original image behind your ring (which I assume has a hollow centre) and the modified version in front.
Select both copies of the car but not the ring. You will then be able to adjust the position, overall size and the amount the car "jumps out".
I'm not quite sure where you want the flag -- possibly in front of the ring but behind the first car. Actually, the flag in the example doesn't look quite right -- you can see its not really "behind" the ring at the bottom. So you may need to make two copies of that too, and put one copy behind and one in front of the ring, the same as the cars.