This tab manages the Digital Elevation file(s) for the relief image.
Download Elevation (EarthExplorer) - Log in, select Digital Elevation under the Data Sets tab and choose GMTED2010. Use the gmted_mea file.
Download US High Res (US National Map) - Log in, select Elevation Products, GeoTIFF format
There are numerous other Digital Elevation sources
Expert Settings
In expert mode, you can have multiple layers. A layer has a name and a set of elevation files.
The layers in a project all share the same project settings (color ramp, hillshade settings, etc.)
The elevation files for a layer should be contiguous and have the same resolution.
Running Preview or Create will only build the Active Layer
To create a new layer: just switch Active Layer and type a Layer Name, then add elevation files.
To change the Coordinate Reference System, switch to expert mode and use the Misc tab.