update CONTRIBUTING.md to include an Intro to Git and GitHub section

CONTRIBUTING.md

@@ -24,7 +24,7 @@ class Foo extends Bar {
 
 ```
 
-- Atleast one newline seperating `namespace`, `use`, and `class` declarations
+- At least one newline seperating `namespace`, `use`, and `class` declarations
 - Spaces around operators and control blocks:
     ```php
     if ($condition) {
@@ -39,3 +39,21 @@ class Foo extends Bar {
 - Files should end with one blank line.
 
 If you're still unsure, then take a look at existing code.
+
+## Intro to Git and GitHub
+
+If you are new to git, GitHub, and the whole open source software community, welcome! Here are some resources for getting started and understanding what it's all about.
+
+- [Try Git](https://try.github.io/levels/1/challenges/1) by Code School
+- [GitHub Help](https://help.github.com)
+
+If you're not particularly fond of the command line, you can get one of GitHub's free GUI desktop apps:
+
+- [GitHub for Mac](https://github.com/blog/1510-installing-git-from-github-for-mac)
+- [GitHub for Windows](https://github.com/blog/1127-github-for-windows)
+
+If you're feeling advantageous, you can become a Git & GitHub master with the [Git Path on Code School](https://www.codeschool.com/paths/git).
+
+There is always the Cachet Gitter chat to ask any questions you may have: 
+
+[![Gitter](https://badges.gitter.im/Join Chat.svg)](https://gitter.im/cachethq/Cachet?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge)