Laravel installation error: "No application encryption key has been specified."

Hi, I have deployed a laravel application to elestic beanstalk here:

http://tomrainey.us-east-2.elasticbeanstalk.com/

but I get the following error message:

"Your app key is missing Generate your application encryption key using php artisan key:generate."

I'm totally new to this, so please be specific. Is this something I have to edit on my local machine or can I do it directly on my AWS installation?

Thanks.