Download the code from the above article and add a new function to the DLL
Code: CPP
void CDll::ATestMethod(HWND hwnd)
{
    CWnd *editbox = CWnd::FromHandle(hwnd);
    editbox->SetWindowText("Shabbir");
}
Now call this method from a dailog based MFC app using the following
Code: CPP
CDll dll;
    dll.ATestMethod(m_edt.GetSafeHwnd());
Assuming m_edt is the DDX_Control of the edit box. If you dont get it let me know your email and I will mail the code to you.