nCtlColor is the control type, edit box, dialog, list box etc..
your dialog box has an edit control??if your are trying to check if some control's id matching use the code
if( IDC_EDIT == pWnd->GetDlgCtrlID())
{
}
if( CTLCOLOR_EDIT == nCtlColor )
{
}
will consider for all edit controls in that dialog. like to set a common color for all edit cntrol.
if( CTLCOLOR_LISTBOX == nCtlColor )//to set a common color for all list control