No, it's not part of your winter shoes. In the CSS tutorial, we talked about using CSS that's already been coded by other people. Bootstrap is exactly that. It's a collection of CSS and JavaScript files that have already been made. All you have to do is include those class attributes and voila, you don't have to do all that CSS coding by yourself!
There are lots of ways to get Bootstrap. A quick Googling and clicking gets you here. You can choose to download all the CSS/JS files. The option we chose for our website is to link to those files with this line:
<link rel="stylesheet" type="text/css" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css">
This just links to the files that are on Bootstrap's server, so we don't have to download it ourselves.
If you do download it yourself, make sure you're linking correctly to the files you downloaded! This may be more powerful if you want to customize the things Bootstrap has already provided and change up their source files.
Hopefully, after reading the HTML and CSS tutorials, you're good enough to go and see what Bootstrap offers you. Go and customize your own websites and write some of your own CSS, try out some of Bootstrap's CSS stuff. If all else fails, Google is your friend! Go have lots of fun :)