Help with adding site plans to the map

I’m trying to add site plans to the map, part of which is already built and occupied.
I’ve looked all round the new editor functions and I can’t see where to upload the plans.
Can someone please either tell me where to add them, or point me in the direction of something that will show me.

Many thanks in advance for any help!

If you have the site plans as a jpeg, you want to use the WME Image Overlays script, which allows you to overlay an image over the editing map, adjust it for scale and angle, and then draw roads using it as a template.