Problems with the views.

Greetings, I have an app running on RoR, this app is of ultra-basic
style (http://www.hackerdude.com/courses/rails/PrimeraAplicacion.html),
this app works as it in the example, but I can not run the views, in the
folder \views, I have \layout and \Main, with their corresponding files
(.html.erb).

The problem is that I want to edit the page (html), but do not know
which I will edited to work, I edited, (principal.html.erb and
application.html.erb) and does not work,
I need help please, thanks.

Wich version of Ruby and Rails do u use now?

Greetings, dear, thanks for answering, my versions.

C:\>ruby -v
ruby 1.9.2p0 (2010-08-18) [i386-mingw32]

C:\>gem -v
1.3.7

C:\>rails -v
Rails 3.0.0