Ghost blog platform doesn't support code highlight. Forunately, there are many solutions out there. One of them is Prism. Prism supports many languages; such as javascript, sql, bash, etc.

Download Prism

Visit http://prismjs.com/download.html
Pick a theme, languages, and plugins.
Scroll down and download javascript and css file.

Edit Ghost theme

Copy Prism javascript file to theme's javascript folder. It should be content/themes/{your_theme}/assets/js.
Copy Prism stylesheet file to theme's stylesheet folder. It should be content/themes/{your_theme/assets/css.

Edit content/themes/{your_theme}/default.hbs.

Add the following tag under {{! Styles }}.

<link rel="stylesheet" type="text/css" href="{{asset "/styles/prism.css"}}"/>

Add the following tag before the body tag.

<script type="text/javascript" src="{{asset "js/prism.js"}}"></script>

Upload the changes to server.

Usage

```html
```

This will output the following:

<!DOCTYPE html>
<html lang="en">
    <head>
        <script>window.console && console.log('foo');</script>
        <meta charset="utf-8" />
        <link rel="shortcut icon" href="favicon.png" />
        <title>Prism</title>
    </head>
    <body><body>
</html>

How to add code highlight to Ghost blog with Prism?