I have putted 2 images together but the car image has to be moved to the ground?

If you want to sit the car realistically

The mask around the car will need adjusting to fully remove the background of the car. Select object gives a starting point but rarely gives a mask that is finished. You can paint on the mask with black to hide elements and white to reveal elements.

Then you need to move and scale the elements taking into account perspective and relevant scale. If those are off it will never look convincing.

Next lighting. To look real, the lighting on the car and lighting on the background should match in terms of direction, colour and intensity. So you will need to use masked curves to change the lighting as required.

Next shadows. The car should cast a shadow on the ground/ You can brush this in on a layer set to multiply blend mode, between the car and the background. Watch the direction - car and background elements should cast shadows in the same direction.

Finally and much more difficult, background elements should be reflected in teh car surface. This will entail warping the background over differentr areas of the car and reducing opacity so you can just see the elements reflected.

Dave