Linux, Mac, Windows...

From the command line (aka Terminal or shell):

gem install bundler

Then make a directory for the site repository, navigate to it in the command line, and clone the repo to your computer:

cd location/to/hold/repo
git clone https://github.com/username/jekyll-repo.git

The cloning url is always listed on GitHub.

From the repository directory, simply run

bundle config set path 'vendor/bundle'
bundle install

This command will use Gemfile (in the repository) to generate Gemfile.lock and install the dependencies specified therein. They will be installed into the local directory ./vendor/bundle/ so that it won't interfere with your system ruby/gems.

To launch a local webserver that will build and show the site, as well as watch for any changes, run this from the command line:

cd path/to/site-repo
bundle exec jekyll serve

Leave that terminal window running (you can see it rebuilding the site every time you edit a file) and point your browser to http://localhost:4000.

Note: Jekyll will not automatically track changes to _config.yml, so if you modify that file, you need to shut down the server (Ctrl+C) and relaunch it.

Just push your changes to the github repo and github will do the rest.

You can (and should) look at existing instances to see how to add content. Here's an outline to get started:

A blog post is simply a markdown file in the _posts/ folder that is categorized as a blog in the metadata. To add a post, create a markdown file with the appropriate filename format (YYYY-MM-DD-name-of-post.md) and fill in the post metadata as follows, being sure to include blog under categories:

---
layout: post
title:  "Name of post"
date:   2015-07-29 23:31:00
categories: blog
---

Markdown formatted blog post goes here...

This site uses a separate blog-posts repo, which is included as a submodule. This keeps the website code neatly separated from content. After adding content in the blog-posts repo, you need to manually update the submodule with

git submodule update --remote

Then commit and push that change to publish to the website.

Pages such as about are simply markdown files in the root directory of the repo. The permalink field can be used to specify the url of the page.

MathJax is supported by Kramdown, but only with $$ as delimiters, both for inline and displayed equations. This means that it will automatically infer whether to display inline or not. For example,

This is some inline math $$ \LaTeX $$. And here's a displayed equation

$$ \LaTeX $$

• 'for loops' go in reverse filename order, so posts --- which are named by date --- get displayed newest first
• github only rebuilds the site if there are changes in the repo --- as such, things like an event sidebar which only shows upcoming events won't automatically update, which could result in past events showing up