Creating a multilingual website

[eluser]Mahn[/eluser]
Hello,

I'm having some problems in creating a multilingual website. I have all of my language files ready in separate folders inside the application/language folder. For every bit of text on the webiste, I'm doing

Code:

echo lang('general_welcome_message');

So now I want to give users the option to change language and store that in a cookie.

Any ideas on how I should go about doing that?

Thanks!