The easiest way to do this is to get your little man seperated from the background image and save him to a seperate file.
Open the background image - switch to the little man and Select - All - Copy to copy the little man image to the clipboard and then paste it into the background image of the car. (you can also tile the view and drag and drop a layer from one image file to the next.
Photoshop will automagically create it on a new layer.
Use your magic wand tool to select the white background you want to delete around the little man image - or you can use the eraser.