I'm having trouble finding how to write to a C++ WinAPI TextEdit control programatically.
Here is my code for the TextEdit control:

case WM_CREATE:
{
  OutputBox = CreateWindowEx(WS_EX_CLIENTEDGE, "EDIT", "", WS_CHILD | WS_VISIBLE | WS_VSCROLL | ES_MULTILINE | ES_AUTOVSCROLL, 10, 90, 410, 235, hwnd, (HMENU)OUTPUTBOX, g_hInst, NULL);
                 break;
}

I already have the buttons which I'm controlling with:

case WM_COMMAND:{}

In Visual Basic I would do:

RichTextBox1.Text = "My output text"

My question is, what is the code to do the same but with this C++ WinAPI control during runtime?