You can select the geographic coordinates by drawing a rectangle on the map or by selecting a place from the picklist

Drawing a rectangle:

• Click on the magnifying glass image on the map
• Click on the map at the desired location and drag untill the desired area is covered
• To clear the bounding box, click on the clear located below the coordinate text-boxes

Selecting from picklist:

• Select either USA or World (by default USA is selected)
• From the scrolldown list, select a place