Pleas say me what does equal this code in win32 project ?

If I get your question properly:

This will tell you how to enable/disable a window:
http://msdn.microsoft.com/en-us/library/5kbfsahf.aspx[^]
In the second link look for the answer from SvenC:
http://social.msdn.microsoft.com/Forums/en-US/vcgeneral/thread/2f269c13-97ab-44e4-b853-17561dc90226[^]

And for messageboxes...
http://msdn.microsoft.com/en-us/library/3tt9e94f.aspx#Y0[^]

Oh, and to know if a string is empty or not...
http://stackoverflow.com/questions/4077940/c-check-if-string-is-empty[^]

Good luck...