On the Control Panel you have the option to install various Twitter Bootstrap plugins. These should load automatically from the Bootstrap project page. If not you can use the Refresh button to reload the list. Also if you want to check for updates or new plugins, use the Refresh button. It will automaticly enable the newly installed plugins.
To enable the Twitter Bootstrap library on your pages you go to the Options button to configure the component. You can select where you want the Bootstrap library to be included. You can also specify if you want the JQuery library to be loaded in addition. There is a version shipped with the package, but you can also opt for the hosted version at Google. If you don't want the Mootools library to be included, you can disable it. If you don't disable the Mootools library, a noConflict code is added.