procedure TForm1.Button1Click(Sender: TObject);
var 
  i: Integer; 
  EncodedStr: string; 
  Header: OleVariant; 
  Post: OleVariant; 
begin 
  // Make the post string URL encoded 
  EncodedStr := 'name=SwissDelphiCenter.ch&text=Test Guestbook entry'; 

  // The post must be an array. But without null terminator (-1) 
  Post := VarArrayCreate([0, Length(EncodedStr) - 1], varByte); 

  // Put Post in array 
  for I := 1 to Length(EncodedStr) do 
    Post[I - 1] := Ord(EncodedStr[I]); 

  Header := 'Content-Type: application/x-www-form-urlencoded' + #10#13; 

  WebBrowser1.Navigate('http://www.swissdelphicenter.ch/en/addguestsent.php', EmptyParam,
    EmptyParam, Post, Header); 
end;