If you need a background image in order to guide you through the modeling of some object or scene, it’s pretty straightforward to do in Blender 2.8. There is a video here too: https://www.youtube.com/watch?v=Jj-C0MkDVjc
First find the image you want to put in the background
Second put your viewport in the right orientation (top, front, side, etc) using the little gizmo in the top right

Then drag and drop the image from Finder (on Max) to Blender

Then it is likely that the image is not positioned in the right place and not at the right scale. You can resize the image using the yellow boxes at each corners of the image when it is selected

You can also place the image in the right spot using the keyboard shortcut “g” then move the mouse. This will move the image.
One difference with Blender 2.79 is that the background images are visible even in 3D views.
