Can't change language for my new theme

Hi everybody.

First of all, i’m really new at this.

I bought a theme and the owner says that it can run with other languages. I want that the outside of the blog (not the dashboard) changes the english to swedish.

And i have tried many things, i already have the swedish language files(SV_sv.po etc) in my /wp_content/languages.. I checked the content.php file and followed the instructions. But it didnt work. Then i installed utf-database converter but then again – nothing. Now some of the titles in my dashboard are missing.

I really want to get my new theme in swedish. Im thinking of starting all over again and remove everything and install wordpress all over again.

If somebody cant help?