Open the picture file in Editor, Expert mode
Use one of the selection tools (Lasso tool or selection brush) to select the object
Place the object on its own layer (CTRL+J)
Get the move tool out of the tool box, use the corner handle of the boundingbox to resize the object, and drag it into position.
Here is a picture of a car, and just the car without background below. Is this the type of thing that you want?