This course "Git Advanced Series ( Part 1 ) : Setting up Sublime Text as the default Git text editor" demonstrates how to install a graphical text editor (Sublime Text) and configure it as the default text editor for Git.
Prerequisites to the course: It's recommended that you complete the course "Git Fundamentals Mastery with GitHub : a complete Hands-on Git Guide" if you are new to Git & GitHub.
Course taking: It's recommended to take the Git Advanced Series in sequence (1 -> 2 -> 3 etc) for better understanding of the concepts