Authoring with Prose.io - AstralDynamics/AstralDynamics.github.io GitHub Wiki
Although it's possible to edit and commit content with GitHubs own interface, prose.io has been tailored to be good for writing and publishing markdown content. This document will describe a workflow for creating and editing posts, without ever having to use the command line.
Authorize

Head to prose.io and sign in with your GitHub account.
Find the Project

Select the Astral Dynamics organisation from the right hand sidebar.
Then find the AstralDynamics.github.io project from the list and click View Project

Make sure you are on the review branch. It should be set by default.
Find the _posts Directory

Posts won't show up unless they are inside the _posts directory. Find it in the list and click to enter it.
Editing a Post
Find the post you want to edit and click it to open it inside Prose's editor. Here you can write markdown and preview the post.

The side menu also gives you a custom editor for working with the metadata fields for each post. This will only show up if the post already has a front-matter metadata header.
Creating a Post
Once inside the posts directory, click on the NEW FILE button to create a new post.
Prose will autofill the posts name with the appropriate format for Jekyll, all you need to do is change the title.
By default a new post won't have any metadata, so you will always have to add the following to the top of the file yourself.
---
layout: post
title: Your Post's Title
author: your_name
---