How to Embed notepad++ into windows form?

public static extern bool SetForegroundWindow(IntPtr hWnd);
       [DllImport("user32.dll")]
       public static extern int SetParent(IntPtr hWndChild, IntPtr hWndNewParent);
       [DllImport("user32.dll")]
       public static extern int SendMessage(IntPtr hWnd, int Msg, int wParam, int lParam);
       [System.Runtime.InteropServices.DllImport("user32.dll", EntryPoint = "SendMessage", CharSet = System.Runtime.InteropServices.CharSet.Auto)] //
       public static extern bool SendMessage(IntPtr hWnd, uint Msg, int wParam, StringBuilder lParam);
       [System.Runtime.InteropServices.DllImport("user32.dll", SetLastError = true)]
       public static extern IntPtr SendMessage(int hWnd, int Msg, int wparam,
       int lparam);
       [DllImport("User32.dll", CharSet = CharSet.Auto)]
       extern static IntPtr FindWindowEx(IntPtr hwndParent, IntPtr hwndChildAfter, [In] string lpClassName, [In] string lpWindowName);
       [DllImport("User32.dll", EntryPoint = "SendMessage")]
       extern static int SendMessageGetTextLength(IntPtr hWnd, int msg, IntPtr wParam, IntPtr lParam);
       [DllImport("User32.dll")]
       public static extern int SendMessage(IntPtr hWnd, int uMsg, int wParam, string lParam);
       public Process proc;

private void Form1_Load(object sender, EventArgs e)
       {
           Process[] pProcess = System.Diagnostics.Process.GetProcessesByName();
           foreach (Process p in pProcess)
           {
               p.Kill();

           }
           proc = Process.Start("notepad++.EXE");
           proc.WaitForInputIdle();
           Thread.Sleep(200);
           SetParent(proc.MainWindowHandle, splitContainer1.Panel2.Handle);
           SendMessage(proc.MainWindowHandle, WM_SYSCOMMAND, SC_MAXIMIZE, 0);
          // SetForegroundWindow(proc.MainWindowHandle);
          // SendKeys.Send("{F11}");
       }

internal void replaceToolStripMenuItem_Click(object sender, EventArgs e)
       {
 SetForegroundWindow(proc.MainWindowHandle);

Win32.SendMessage(proc.MainWindowHandle, SciMsg.SCI_INSERTTEXT,0, "Hello, Notepad++... from .NET!");
        }