alex-romanov,
<!DOCTYPE html>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
<style type="text/css">
</style>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script>
<script>
$(function() {
var index = 1;
$('tbody tr td:nth-child(' + (index + 1) +')').css({"backgroundColor": "#FF0000"});
});
</script>
</head>
<body>
<table width="400" summary="" >
<thead>
<tr>
<th>Title 1</th>
<th>Title 2</th>
<th>Title 3</th>
</tr>
</thead>
<tbody>
<tr>
<td>Cell 1.1</td>
<td>Cell 1.2</td>
<td>Cell 1.3</td>
</tr>
<tr>
<td>Cell 2.1</td>
<td>Cell 2.2</td>
<td>Cell 2.3</td>
</tr>
</tbody>
</table>
</body>
</html>