{....} 

  private 
    procedure SearchAndHighlightText(aText: string); 
     
{....} 

procedure TForm1.SearchAndHighlightText(aText: string); 
var 
  i: Integer; 
begin 
  for i := 0 to WebBrowser1.OleObject.Document.All.Length - 1 do 
  begin 
    if Pos(aText, WebBrowser1.OleObject.Document.All.Item(i).InnerText) <> 0 then 
    begin 
      WebBrowser1.OleObject.Document.All.Item(i).Style.Color := '#FFFF00'; 
      WebBrowser1.OleObject.Document.All.Item(i).ScrollIntoView(True); 
    end; 
  end; 
end; 

procedure TForm1.Button1Click(Sender: TObject); 
begin 
  SearchAndHighlightText('some text...'); 
end;