Below is a quick method for creating collages in Photoshop. In this example, I am only using two images (aka a "diptych") but you can easily add as many images as you would like using the following method.
EXTEND THE CANVAS
With your first image selected, you will need to extend the size of your canvas by selecting Image>Canvas Size:
By clicking on the arrows, you are selecting the direction in which you will be extending your canvas:
For this example, I am extending my canvas to the right:
When I am extending my canvas, I like to switch my dimensions from pixels to inches, just for ease of use. My canvas (original image size) was 5.906 inches to begin, so I want to make my canvas larger in order to accommodate my next image, so I am going to extend it to 10 inches just so I have plenty of wiggle room:
I am also setting the Canvas Extension Color to white. This will be the color of my borders in my collage. You can set it to white, black, gray or a custom color:
ADD THE SECOND IMAGE TO THE EXTENDED CANVAS
With your original image which as the extend canvas selected, drag and drop the next image onto the extended portion of your canvas:
You can use the move tool, highlighted below on the top left corner, to place the image in the area where it should be. Since my second image is a vertical, I need to resize it a bit by making it smaller. In order to avoid warping your image, hold down the shift key to retain the original proportions as you resize your image:
You can now use the Rectangular Marquee tool (circled below) to select the portion of your image that you would like to retain, then crop any remaining areas that are unwanted:
If you liked this tutorial, we have lots of other great Photoshop tutorials just for you!