You’ll find this post in your _posts directory. Go ahead and edit it and re-build the site to see your changes. You can rebuild the site in many different ways, but the most common way is to run jekyll serve, which launches a web server and auto-regenerates your site when a file is updated.

To add new posts, simply add a file in the _posts directory that follows the convention YYYY-MM-DD-name-of-post.ext and includes the necessary front matter. Take a look at the source for this post to get an idea about how it works.

Jekyll also offers powerful support for code snippets:

'use strict';
var markdown = require('markdown').markdown;
function Editor(input, preview) {
  this.update = function() {
    preview.innerHTML = markdown.toHTML(input.value);
  };
  input.editor = this;
  this.update();
}

You can add inline code just like this, E.g. .code { color: #fff; }

pre {
  background-color: #f4f4f4;
  max-width: 100%;
  overflow: auto;
}

Check out the Jekyll docs for more info on how to get the most out of Jekyll. File all bugs/feature requests at Jekyll’s GitHub repo. If you have questions, you can ask them on Jekyll Talk.