Help with "No route matches "/MyTest/" with {:method=>:get}"

I just started working with Ruby. Anyways I can't seem to figure out
how to have this message disappear. I was reading a tutorial and based
on it, when I type in http://localhost:3000/MyTest/ it should say
whatever I have written down on my my_test_controller.rb file.

I first ran: ruby script\generate controller MyTest

then I edited the my_test_controller.rb file

It currently says:

try
http://localhost:3000/my_test/