can't get rid of loud freakin dinging noise

It beeps because, being a single line, pressing enter is considered an attempt to insert another line.

On dialog boxes, the Enter key is trapped by the dialog procedure and sent to the default pushbutton (if any), otherwise left to the edit control itself.
On other window, such "trapping" requires a messge-loop that check the presence of a dialog message before dispatching to the focused window.

Something like

/* Window procedure definition */
LRESULT WINAPI CALLBACK winproc(HWND h, UINT m, WPARAM w, LPARAM z)
{
    ....
}


/* may be WinMain, _tmain, _tWinMain or whatever entry point */
int main() 
{
    /* Class registration stuff */
    WNDCLASSEX wcx = { ..... };
    ....
    RegisterWindowClassEx(&wcx);

    
    /* WIndow Creation */ 
    HWND hwnd = CreateWindow( .... );
    ....
    
    /* messge loop */
    for(;;)
    {
        MSG msg;
        if(GetMessage(&msg,0,0,0)<=0) break; //< exit on error or "quit" 
        if(IsDialogMessage(hwnd,&msg)) continue; //< skip regular dispatching
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    return 0;
}