Reply To: the background images not showing up?

@blenderggg221 in 2.8+ Background Images are handled differently by Blender; they are  separate objects, you need to add them ‘by hand’: in Front Orthographic (for instance) SHIFT+A > Add > Image > Background. 

Scale it to the correct size and adjust the settings to your liking here:

Copy the Image and rotate it 90° around the Z-axis to get the side view and one more time for the top view.