I merely provide a translation-ready PO file with this theme that you can then take and translate using software such as Poedit (http://www.poedit.net/). I have not translated a WordPress theme myself, nor do I really know how to translate one, so I am not the best resource to help you with this specific task. I do know that the PO file I provide works, because hundreds of customers have successfully used it to translate their themes. To get much better information than what I can provide you, start with this resource: http://codex.wordpress.org/Translating_WordPress, and then ask any specific questions on WordPress Answers: http://wordpress.stackexchange.com/, or the WordPress support forums: http://wordpress.org/support/.
Flavor, Steam, and Explicit users:
Here are steps to translating the theme. Special thanks to MichaÅï¿½ Kowalski for compiling these steps!
1. Download and install Poedit
2. Open "en-US.po" file
3. Check a line you want to translate, and write a word in your language in Translation section.
4. If your translate is done, click File > Save as and name it correctly to your language, for example "pl_PL.po" for Polish language.
5. Then generate a .mo file clicking File > Save as, name it correctly to your language, for example pl_PL.mo, and thats it.
6. Upload these two files to your theme directory, "wp-contet/themes/THEME_NAME/lang" and you are done.
If you have issues using Poedit you can try Transposh instead which has been used successfully by some IndustrialThemes customers.