How to create an RGB composite In envi

Satellite imagery is captured in multiple wavelengths of reflected light otherwise known as image 'Bands'. We can combine three image bands into one picture by display each band as either Red, Green or Blue.
In this tutorial I show you how to create an RGB composite Image within envi software.

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When I am trying to add Landsat bands it is asking me about ENVI Header info. What to fill in Sample, Lines and Band?