In the map pane on the right hand side of the app, click on Add area > Upload new area
Drag and drop your file into the box, or click Choose file to select files from your device. This file must be a GeoJSON, GeoPackage, KML, KMZ, CSV or a zipped shape file.
You can choose to Save file to Assets to use the file across multiple projects and manage them in a central place.
Learn more: Uploading a feature collection to Assets
If your file contains multiple areas and has at least one attribute, you can choose to categorise your areas by an attribute.
For example, if your areas have a ‘name’ attribute, each area with a unique name will be added as a separate area.
Uploading larger files
If your file is larger than 800KB you will receive an error window with an option to upload your area to Assets.
In general, if you need to work with files larger than 800KB, you should upload the file to your Assets via the Assets page. Uploading large files may take a while, but once it's finished uploading, you can add the area to your project (i.e. on the map) by clicking Add area > Choose from Assets.