When you created the project, you made the wrong choice of application type. When asked whether your project was a console application or a windows application or a DLL or a static library, you made the wrong chose windows application (wrong choice).
Go back, start over again, go to File -> New -> Project -> Win32 Console Application -> name your app -> click next -> click application settings.
For the application type, make sure Console Application is selected (this step is the vital step).
The main for a windows application is called WinMain, for a DLL is called DllMain, for a .NET application is called Main(cli::array ^), and a static library doesn't have a main. Only in a console app is main called main
From MSDN:
error LNK2019: unresolved external symbol _WinMain@16 referenced in function ___tmainCRTStartup[
^]