1. Drag the image you want to use to your Fill Your Head Workspace, by using the Move Tool - next to the Marquee. It will be small but as long as it was a high resolution image, you can use FREE TRANSFORM (Control T) to make it bigger. REMEMBER, you need to hold down the SHIFT key to keep it in proportion.
2. In order to get the pictures behind the cutout, you have to drag them ABOVE the layer in the LAYER PALETTE. Think of it as a pile of papers - the top of the pile is on top, the bottom can't be seen.
3. You can use filters and opacity to add visual interest to images as you layer them up