I believe background and reference images do not contribute to the final render. To get an image in the render you have two options.
1) Render from the view port. In the 3D view you can go to View > Render Viewport Image or Render Viewport Animation. This may not be ideal if you have more complicated materials and lighting, so I would recommend the following....
2) Use Import Images as Planes Addon. This comes included in Blender, you just have to enable the add-on in user preferences. Then in the 3D view, you can Shift+A or Add Mesh and in the Images sub-menu, you should now see "Images as Planes". In the File Explorer window where you select the image, there are several options in the lower left hand menu, including align to camera.
Both have the advantages and disadvantages. The first method allows you to see your images in Wireframe or Solid* mode, which is great for reference, while the second method is better if you want to actually use an Image in your final render.
Hope this helps. Let me know if you have any questions.
*Update: I mentioned earlier you can not view an Image Plane in Solid mode, but if you select "Texture" as Color in the Solid Shade drop-down menu (see attached), you can view the Image in Solid Mode.