procedure TForm1.Button1Click(Sender: TObject);
var
  LoginInfo: TStringList;
  Response: TStringStream;
  STR:string;
BEGIN
try
    LoginInfo := TStringList.Create;
    Response := TStringStream.Create('');
    LoginInfo.Add('vb_login_username='+Edit1.Text);
    LoginInfo.Add('vb_login_password='+Edit2.Text);
    IdHTTP1.Post('http://site/login.php',LoginInfo,Response);
    str:=IdHTTP1.Get('http://site/');
    Memo1.Lines.Add(str);
  finally
    begin
      Response.Free;
      LoginInfo.Free;
    end;
  end;
end;