Assuming you have been following this video series so far you should now have a Git Project all setup and ready to go as we will not cover basic Git Workflow.
The next video tutorial will be divided into two parts. The first will be about Git Workflow with the later part talking about more advanced features. Once you cover this video you should gain an understanding about making changes to a file and marking it ready for commit. Follow the video tutorial below to get started.
Basic Git Workflow Video Tutorial
Direct Video Link
Follow the video tutorial to learn about the basic concept of Git Workflow.