procedure TForm1.btn2Click(Sender: TObject);
var
  ovElements: OleVariant;
  i: Integer;
begin
ovElements := Wb1.OleObject.Document.forms.item(0).elements;
for i := 0 to (ovElements.Length - 1) do
if (ovElements.item(i).tagName = 'textarea') then
ovElements.item(i).value:='Marsel';
end;