1. Select a suitable background, a locate all of the additional images that you will need: monster, people screaming, cars etc...
Have these stored in a folder on your desktop.
2. Using the Quick Selection Tool (W), select and copy the individual pictures onto your background scene, making sure that each image is placed into a New Layer.
3. Place your people/monsters into the scene, ensuring that you keep them to an accurate scale. This can be achieved by going to Edit>Transform>Scale or hitting (cmd+T), hold down the Shift key to maintain correct aspect ratio.
4. Check to see how the pictures look on the background image by turning on/off the Indicates Layer Visibility button, located in the Layers Console on the right of the screen.
5. Once everything is in place and scaled correctly, you will need to flatten the image. Go to Layer>Flatten Image or (cmd+F). This will squash all of the individual layers into one, create a smaller file size.
6. In the Layers Console, select New Adjust Layer and choose Black & White. This will remove all colour from your flattened image. It is important that you save your image as a jpeg if it's complete, do this by going to File>Save as and selecting JPEG in the Format box. If you have not finished editing, save it as a Photoshop psd. (also in the Format box).
