TCHAR is nothing but declaring char array. Something Like TCHAR *str ="Your string"; or even TCHAR str[] ="Your String";

For GetBuffer it should be something like
CString hello_string="Hi This is my 1st Document View";
pDC->TextOutW(0,0,hello_string.GetBuffer(),hello_string.GetLength()  );
I thought I was clear enough with the above post and so not gave any example.