A few references you might find useful:

1. Shortcuts for navigating the command line
2. GitHub Desktop for visualizing changes
3. Git Book
4. tryGit: Git Challenges from GitHub + CodeSchool (aka an interactive training program)
5. Git Handbook
6. 9 GitHub Lists for Testing
7. 18 GitHub Projects for Testing
8. Practice Using Selenium Now

Also see GitHub Page Examples

Many of these projects have labels for first time submitters. Using these labels will get you better responses from the project’s members

• TestingConferences.org - A simple list of software testing conferences and workshops published collaboratively with the testing community.
• Tech Community Slacks - This is a list of tech community Slack teams, organized by region. If your group has a Slack team, you can add it here.
• Wordpress.com Desktop App
• Babel, Node / NPM, Rails