I want to be able to download high resolution 3 arc degree resolution (90 meters) from NASA's earthexplorer.gov site. However it is a bit confusing for a beginner like myself. I want to be able to do this for my country i.e. India. I go here <http://earthexplorer.usgs.gov/> and by pressing shift I zoom into the area of interest by creating a rectangle. Then it displays 4 coordinates and then I ask for datasets. I get so many options and each are of very small sizes. Am I supposed to download all of it or just any one of it ? If I am supposed to download all of it is there a way to do it all in one download ? I presume then I will have to use progamming code to concatenate these separate .hgt files together.