I am trying to upload an image to my ArcGIS Urban plan so that I can overlay it on the map and consequently design zones and parcels around it. I understand how I can add a layer to my map after it is in "My Content" (going to "Manage" and then to "3D Base Layers," clicking the pencil and selecting the layer) but I am at my wit's end trying to figure out how to upload the image into "My Content" as a layer/map in the first place. Does anyone have any advice here?