Hi Richard, I can see that image and I've added a service entrance to OSM to give you a start. Please check for it's correct location, I've also squared up the building.

As for contributing to OSM, from experience I'd say first decide if your mapping will be occasional editing for which the iD editor will be OK, you've already used it. Or more serious dedicated mapping that might need a more comprehensive editing tool like JOSM. You can of course use both. But JOSM is by far superior though there is much more to learn.

Please feel free to ask any questions. You can directly message a mapper by clicking on their name, as shown above, like mine. 

Need help just ask, Regards Bernard.

