After forking, click the Settings button on your new repository and change the repository name to username.github.io -- make sure that username is replaced with your GitHub username!
Hosting your Jekyll blog on your GitHub user account takes care of a LOT of the hard work for us. You'll see shortly.
You can quickly update a lot by simply editing the configuration file. Go to the base directory and open up _config.yml. In there you'll be able to edit your:
Go to the _posts folder and simply edit the one that's there to create your first blog post! Jekyll pulls the date of the post from the filename, so you can edit that to today's date.
Follow the latest [GitHub Pages Custom Domain Guide](https://help.github.com/articles/setting-up-a-custom-domain-with-pages) to set up your custom domain name. I've created the CNAME file already, so that you can easily edit it within the repository.
I'm working on a portfolio site theme right now, and more to come after that. If you'd like me to let you know when I release a new theme, just [drop me your email for updates](http://getresponse.com).