Use the Quick Selection Tool to select something in the background image you want to replicate. Copy and Paste.

Use the Free Transform Tool to resize the people. You can also use Transform to flip them horizontally to add interest and variation.

Use the Eye Dropper tool to select a color you would like to use to fill in the silhouette of one of the couples.

With the layer selected that corresponds to the couple you'd like to fill, make a New Fill Layer.

With the Fill Layer selected, create a Clipping Mask.