First things first, you'll need to download and install the T3 framework plugin and the blank template to start off with. So lets head over to http://t3-framework.org/ and click the Downloads button at the top of the page. There are a few different option on this page, allowing you to download the various files and documentation you might need. The T3 Framework Package is a great starting point that provides you with the T3 framework itself, and a very usefull template called T3 BS3_Blank which is based on the Bootstrap 3 framework. Further down the page you can download the template seperately, or the T3 framework seperately.