Rather than working directly on the photo itself, let’s start things off by creating a new blank document. This will allow us to create our effect at any size we need rather than trying to work within the dimensions of the photo itself. Go up to the File menu at the top of the screen and choose New, or simply press the keyboard shortcut Ctrl+N (Win) / Command+N (Mac). Either way brings up Photoshop’s New Document dialog box. Enter in the dimensions you need for your effect.
For this tutorial, I’m going to enter in a standard size of 6 inches for the Width and 4 inches for the Height, but of course you can enter whatever dimensions you need. For the Resolution, I’ll enter 240 pixels/inch, which should give me professional quality print results if I decide to print the image later. The most commonly accepted resolution for professional print results is 300 pixels/inch, but you’ll often find that you can get away with less than that without any noticeably loss in quality. I typically use 240 pixels/inch with my images: