c++ - LNK2019 Error Cocos2D-X

I got a LNK2019 error in Visual Studio 2013 when I changed a file.
When you create a new Cocos2D-X project you start with a basic project with 2 cpp files and 2 header files.

I changed the HelloWorldScene (header & cpp) file to another name. Now I am getting a LNK2019 error :

Error   5   error LNK2019: unresolved external symbol _main referenced in function ___tmainCRTStartup   C:\Users\bette_000\Documents\GitHub\TheAdventuresOfJos\MyGame\proj.win32\MSVCRTD.lib(crtexe.obj)    MyGame
Error   6   error LNK1120: 1 unresolved externals   C:\Users\bette_000\Documents\GitHub\TheAdventuresOfJos\MyGame\proj.win32\Debug.win32\MyGame.exe 1   1   MyGame

I used to have these files:

• AppDelegate.cpp (& .h)


• BeginMenu.cpp (& .h)


• globals.h


• HelloWorldScene.cpp (& .h)


• OptionsMenu.cpp (& .h)

This worked. But since I changed the name of HelloWorldScene.cpp (& .h) to MainApp.cpp (& .h) I got this error.