Problems with translation Poedit

Hi!

Im quite new to wordpress and could use some help. I’ve been trying to translate my the theme for my website to Norweigan for a few days now in. I’ve been using Poedit to create a new .po and .mo file called nb_NO, everything so far so good. When the new .po and .mo file is done the next step is to change the wp-config file and change the define(‘WPLANG’, ‘en_EN’);
to define(‘WPLANG’, ‘nb_NO’); . My problem is that the sentence define(‘WPLANG’, ‘en_EN’); doesn’t exist. I’ve tried to just add the sentence but nothing happens, the theme is still in English. Does anyone know what I’ve done wrong and how it can be resolved?? Very thank full for any answers I can get. Also in the themes /languages file there’s a number of different .po and .mo files for example english, russian and french, should I delete these?

Regards