To begin working on anything, you need one of two things: a new image or an existing one that you opened.

To create a new image, select File > New, or press <Ctrl>N (Windows) or <Cmd>N (Mac OS).

A dialog should pop up prompting you to define five general elements for creating a new image.

• You may name the image now, or later, when you save the image.
• You may predetermine the size of your image in many ways. Photoshop offers preset dimensions or you can customize your own size, using many types of measurements (including pixels, centimeters, inches, and millimeters to name a few of the most digitally popular).
• A resolution of 72 ppi (pixels per inch) is generally used for Internet purposes. Anything higher than that can be used for images requiring high quality, such as those destined for print or video.
• For the purposes of this tutorial, we'll stay with the RGB (Red Green Blue) color mode, which offers general colors. There are also other preset modes that offer different schemes such as grayscale. As you probably have guessed, choosing different modes limits some of the color ranges.
• The Contents section lets you decide what the initial background color of the new image will be.