Depends on what you want to do with it.
If you want to use it as a guide to draw something else, you probably want to use an Image Plane.
Go to an orthographic view (top, left, front) and View > Image Plane > Import Image.
If you want to use it as a texture on an object, you'll attach it to a material by clicking on the checkerboard next to the Color of the material and using a File node to load that photo.
I can show you how to do either of these any time you want!