Private Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Long
Private Declare Function FindWindowEx Lib "user32" Alias "FindWindowExA" (ByVal hWnd1 As Long, ByVal hWnd2 As Long, ByVal lpsz1 As String, ByVal lpsz2 As String) As Long
Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Integer, ByVal lParam As Any) As Long
Private Const WM_CHAR = &H102
Private Const WM_SETTEXT = &HC
Private Const VK_RETURN = &HD
Private Const EM_SETSEL = &HB1
Sub ui()
Dim hwnd As Long, wnd As Long
    Call Shell("notepad", vbNormalFocus) 'запускаем блокнот
    hwnd = FindWindow(vbNullString, "Безымянный - Блокнот") 'получаем hwnd окна блокнота по заголовку
    wnd = FindWindowEx(hwnd, ByVal 0&, "Edit", vbNullString) 'получаем hwnd текстбокса блокнота
    Call SendMessage(wnd, WM_SETTEXT, 0, "Привет") 'изменяем текст в текст боксе на "Привет"
    Call SendMessage(wnd, EM_SETSEL, 6, "") 'сдвигаем курсор на 6 знаков
    Call SendMessage(wnd, WM_CHAR, VK_RETURN, vbNullString) 'нажимаем Enter
End Sub