Languaje settings on 6.1.6 version

Hello, i have installed 6.1.6 boonex version, i have a question, i change the default languaje to spanish and it do not  work, somebody can tellme what is the right way to change the languaje.

have translated the basic englisch file or made a new one?
have you compiled the translated language file?

I have created a new languaje copied from english, and compiled and it do not make changes. i test downloading the mysql script with every word in spanish, and runit on server and looks ok. I go to the admin page a see the languaje created ok, and if i edit it every word is ok, but i put it like default site languaje but still appearing every thing in english. i have copiled it and put it again in default site languaje and still in english