Executing external exe in a child window (cpp,win32)

i have written a simple win32 program say abc.exe. I have added a button in it, clicking on which an external exe (say xyz.exe) should start. But the original program i.e. abc.exe should be inaccessible while xyz.exe is running.(same as in the case of message box.. the parent window is inactive unless message box is closed). How can do it ? It would be great if you could post an example code.