C programming WinAPI32 - How do I get a windows HWND and send it messages?

1. How do I send messages and get handlers to other windows in QT ?
2. Any videos on basics such as settings strings to messagebox \ labels \ input fields etc ??
   

I've googled this but am not getting any straight answers so I registered here.

ANy videos on this by chance? Can I build windows programs while on my Ubuntu laptop ? What's the problems I will face?
Can I run them with Wine and it will work all the same?

The Qt library does not stop you accessing any part of the Windows API to obtain a Windows handle to a remote window and do anything the API allows. You do this is in the same fashion as shown in any Windows API tutorial - it has little to nothing to do with Qt.

You can build Windows programs on Linux boxes using the MingW suite to cross-compile. You may be able to run the resulting binary in Wine, and you may get the same result as a real Windows bo it depends on whether you stay with in the limitations of Wine.