How to send cookie value from rails app to browser - newbie

Hi

I am writing a multilingual app, now from sasa’s ruby
gettexthttp://manuals.rubyonrails.com/read/chapter/105instructions,
i have made it so far that it works if i manually type alsong
with the url ?lang=en or ?lang=fr , but i don’t know how to have rails
do
that automatically , i tried to read some material on cookies and
sessions ,
but could not understand it properly …