APPG: Visual Studio: Debugging technique. Common coding mistake & how to fix it.

Explain how to navigate in Visual Studio? How to debug? And, one very common coding mistake made by beginners. The details are:

- How to open a form? How to navigate?
- How to reset Windows layout
- How to debug? Important step: DOUBLE CLICK the error so that VS will spot the mistake and place a blinking cursor at your code.

- Common mistake made by beginner.
Do NOT modify the code automatically generated by e.g. radioButton_CheckedChanged. You will corrupt your program. How to fix this error?