Every good Photoshop document has layers, and the best ones have masks, which are displayed through alpha channels. When it comes to masks, there’s a saying that “white conceals and black reveals,” which means that when editing a mask, the white is the part that is editable while the black is the part that remains untouched. This allows photos to be layered on top of each other in an endless variation of ways.
In the first Photoshop image, a photograph of Nadia Comăneci, the most influential gymnast of all time is inserted over a masked image of her gold medal (well, one of her gold medals). This was accomplished by selecting the medal with the quick selection tool, making it a mask, and then inserting it above a mask of just her body. The background was also edited out and given a blue blur for a pop of color.
In the second Photoshop image, a piece of text (my name, Sarah Munroe) is combined with an image of my favorite animal, a peacock. The name was made into a mask by making the text white on black, and then it was placed under the layer of the peacock image so that the peacock would shine through the name.
Finally, in the last image, the image of my face is inserted above an image of Scarlett Johansson on the red carpet holding her new Tony Award. A mask was used to make the Tony award appear over my hair, because otherwise the hair would block it since the image of my face is layered above the image of Scarlett’s body. The hue and saturation were also edited to make the skin tones match a little better, and hair from the left side of my face was copied to the right side so that I’d appear to have a fuller head of hair. The resulting image isn’t completely believable, but the concept was accomplished.
Photoshop, like any skill, takes lots of practice. Understanding the basic concepts such as layers, masks, and channels, as well as the general tools and how they work is the first step to become an excellent graphic designer.