I found a somewhat matching c4d background and took my clone stamps off of that. I am still amateur with clipping masks. So I use the clone tool(pick a good brush, make sure the correct layer is selected, then hold alt to 'clone' that portion of the picture). Now go to a new layer and just click that stamp on your new layer. Try different brushes and opacity settings. Once you clone what you want, duplicate your background image, hide one of the layers, and then smudge the other one.