It is a very dry region. Start by downloading and unzipping the data. Examine the area in, first, a false colour image. Then as a colour IR image. This is just to get a bit of familiarity with the area.
Vegetation is shown quite clearly in the colour IR image.
Explain this difference. Compare and contrast the false colour and 751comp images. Where is 751comp a superior image for geologic interpretation. Now, let's look at a few ratio images. To generate these, you will use the vegetation index command - just substitute the proper bands.