Open the TDDP using the link https://portal.tern.org.au.
You can select Map based search bar to search TERN data using map, this map search will provide options to select data by drawing region, a polygon on the map, search using Longitude & Latitude.
Selecting the Map Search will display the page as;
Select icon from the map view to draw a polygon on the map.
Single click will highlight an area on the map, drag the cursor to your desired area on the map, double click will end the drawing.
Hit 'Go' button to search the polygon you selected on the map, the data search result should display like below;
Access the data by selecting the title of the data search result.
To clear the selection from the map, select and it will clear the region on the map.