You would start at https://www.inaturalist.org/places/new and upload a KML of the boundary. Note that very complex boundaries or large areas have to be added by staff (via help@inaturalist.org), but you can try it yourself first. Some recommendations:
- be sure you have thoroughly searched for potential existing places that would serve your needs first. We already have a lot of duplicates or near-duplicates on the site.
- if there are similarly named places already in iNat, make sure the name you use is distinctive and descriptive enough that other users won’t confuse it with something else.
- choose the Parent place carefully, as this can affect how some place-based changes propagate through the system. Ideally it should be the smallest existing place that completely encloses your new place, and one that seems likely to be stable. For example, when I created this place, it was about 75% in California and 25% in Nevada, straddling two counties in each state. Southwestern United States was one parent I considered, but Great Basin Desert was smaller, still inclusive, and seemed likely not to be changed much, so that’s what I went with.
- Simplify your polygon geometry as much as you can, to avoid the aforementioned size limits. The current guidance is for
KML of the place boundary. You can make one using Google Maps, Google Earth, or most GIS applications. Must have at least one polygon be under 1 MB (5 MB for site curators), and have an area smaller than the US state of Texas.
If you are going for bigger, you will need to contact staff.