Make Joomla 3.1.5 website multilingual

Hi, We have a website already setup with Joomla 3.1.5 and a template. A bit of the work is done but for some reason the multilingual part doesn't seem to work properly. We basically have a splash page with 5 language selections (2 already added) and once the user selects their language, we want them to access the website in that language and be able to switch languages if they wish from a drop down menu. This project needs to be done within 3 hours today and can pay up to $40 if completed properly and explained how to do it. Thanks.