The first step to do is go to the official Bootstrap website. You have the download button right there in front of you. You can download bootstrap in the form of a zip file or you can download it using package managers. Read all about it in How to Install Bootstrap.What is the current bootstrap version?
The current major stable version of Bootstrap is 3, which is backwards incompatible with Bootstrap 2. Besides version 3, Flask-Bootstrap is maintained for the latest version of Bootstrap 2 (although you should not expect new features, only bug fixes).What is included in Bootstrap?