I could not find the rhino Material Editor…
Which version of Rhino are you using? If you have a specific render plugin you are trying to use that will also determine what material and environment editors you have access to.
Thank you for your answer.
I am using Rhino 4.
When I type MaterialEditor nothing happens.
So, I do not have the default MaterialEditor that the program has.
It sounds like you are just missing the RDK plugin for Rhino 4 which provided a material editor http://wiki.mcneel.com/labs/rendererdevelopmentkit10
I would suggest using Rhino 5 instead though which will have these tools by default in their most recent versions. You can have the eval of Rhino 5 on your machine without removing Rhino 4.