How can I open a .cpp file from a specific location using text editor of my choice?

edit

I am working through the second set of beginner tutorials and am stuck on part 7 of creating a workspace. It says "You can modify turtlesim in your overlay by editing the title bar on the turtlesim window. To do this, locate the turtle_frame.cpp file in ~/ros2_ws/src/ros_tutorials/turtlesim/src. Open turtle_frame.cpp with your preferred text editor."

I am new to coding in general and do not know how to do any of this and cannot find tutorials on it.

Thanks!