To use this code please create a new module or add it to your existing project.

Function ConvertToSecureString(ByVal str As String)
        Dim password As New SecureString
        For Each c As Char In str.ToCharArray
            password.AppendChar(c)
        Next
        Return password
End Function
Sub Main()
       dim username as string = "Administrator"
       dim password as SecureString = ConvertToSecureString("my password")
       dim domain as string = Nothing
       dim filename as string = "notepad.exe" ' %SYSTEMROOT%\system32
        Try
            System.Diagnostics.Process.Start(filename,username, password, domain)
        Catch ex As Win32Exception
            MessageBox.Show("Wrong username or password.", _
		"Error logging in as administrator", MessageBoxButtons.OK, _
		 MessageBoxIcon.Error)
        End Try
End Sub