Help requested with Geo Tiles Viewer and elevation data

I'm attempting to import raster data using the NIMAMUSE Raster Importer as described in the GTV readme file. I believe I've generated the 6x5z20.hdr and 6x5z20.fil files in the proper manner but I'm not sure where to go next. The readme states "...files are imported when no node is selected and both files exists in the same folder. output is then 6x5z20.tga." I'm asuming this means place the .hdr and .fil in the same folder with the geo tiles viewer along with the .tag file. When I select terrain elevation import without selecting a node, I get the message "select node, not map".Anyone have any suggestions?Thanks,Rick