MFC creation of simple windows

You have set your project to build a Unicode application (which is the default).

For such all string literals have to be Unicode (wide char) strings which requires prefixing them with an L:

MFC_Tutorial_Window() { Create(NULL, L"MFC Tutorial Part 1 CoderSource Window");     }

If you want to support non Unicode builds too, you can use the _T() macro for such strings which is then resolved according to the project settings:

MFC_Tutorial_Window() { Create(NULL, _T("MFC Tutorial Part 1 CoderSource Window")); }