Exporting your plans is a very useful feature if you wish to work in other GIS type programs. It is also a way to move plans from one map to another.
Please note you are only exporting the plan features you have created, the export does not include the base map.
In the top right of the screen click on Export.
The export menu will open. Select what you would like to export then pick your Export as option from GeoJSON, KML, Shape file or DXF, click export.