[uMap] How to draw a polygon based on an OSM node

[Guillaume]

Hi,

I'd like to draw a polygon in Umap using an existing OSM node.


For instance, in the Umap below you can see that polygons are based on 
Paris districts, which are nodes on OSM :

http://umap.openstreetmap.fr/en/map/municipales-lump-et-ses-dissidents-a-paris_6302#12/48.8512/2.3456

Example district node :

http://www.openstreetmap.org/relation/9525


I don't find any tutorial about how to do it.

Cheers,

Guillaume