Go to twinery.org, the website for TWINE. You'll find a lot of great information on that site, but getting started is very easy. You may choose to begin by either using it online or downloading the program (see the links pointed out in the image below). It is better to use the download version for long term use, but they work the same. Note: if you use the online version and clear your internet browser cache, you'll lose your IF!!!
twinery.org. Where to download TWINE or access it online.