Hello guys this is SpiderWoman- recently I got a request from @kitkatclark to do a chapter on this so here it is. To make the silhouette I use Adobe Photoshop Mix (app)
First I cut out the background of the image.

then I press adjust and turn the exposure all the way down and the contrast all the way up.

After that I find the image I want to layer on the silhouette. I place the image under the silhouette and press blend picking the overlay option.

After that I merge the silhouette to the background image so I can cut out around the silhouette.

The final product looks like this: