What I would've done (using Paintshop Pro, at least), is get the background image you wnat to put the object into, trace around the object you want, copy it from the original image, and then paste the object onto the other image.

--or--

You could trace the object you want, promote it to a new layer, and then insert a new background under it ("Paste As New Layer"...or something like that).

...Now that I've thoroughly confused you, I know someone else will chime in -- one who actually uses Photoshop.