The value is in milliseconds so ...
DWORD ticks = GetTickCount();
DWORD milliseconds = ticks % 1000;
ticks /= 1000;
DWORD seconds = ticks % 60;
ticks /= 60;
DWORD minutes = ticks % 60;
ticks /= 60;
DWORD hours = ticks; printf("%d:%02d:%02d.%03d\n", hours, minutes, seconds, milliseconds);
If you don't care about milliseconds, MFC's CTimeSpan class may work for you.
CTimeSpan span(ticks/1000);
printf("%d %02d:%02d:%02d\n", span.GetDays(), span.GetHours(), span.GetMinutes(), span.GetSeconds());