You can dynamically add and delete table rows like this in the image using jQuery..
Here is html part...
<form id='students' method='post' name='students' action='index.php'>
<table border="1" cellspacing="0">
<tr>
<th><input class='check_all' type='checkbox' onclick="select_all()"/></th>
<th>S. No</th>
<th>First Name</th>
<th>Last Name</th>
<th>Tamil</th>
<th>English</th>
<th>Computer</th>
<th>Total</th>
</tr>
<tr>
<td><input type='checkbox' class='case'/></td>
<td>1.</td>
<td><input type='text' id='first_name' name='first_name[]'/></td>
<td><input type='text' id='last_name' name='last_name[]'/></td>
<td><input type='text' id='tamil' name='tamil[]'/></td>
<td><input type='text' id='english' name='english[]'/> </td>
<td><input type='text' id='computer' name='computer[]'/></td>
<td><input type='text' id='total' name='total[]'/> </td>
</tr>
</table>
<button type="button" class='delete'>- Delete</button>
<button type="button" class='addmore'>+ Add More</button>
<p>
<input type='submit' name='submit' value='submit' class='but'/></p>
</form>
Next need to include jquery...
<script src='jquery-1.9.1.min.js'></script>
Finally script which adds the table rows...
<script>
var i=2;
$(".addmore").on('click',function(){
var data="<tr><td><input type='checkbox' class='case'/></td><td>"+i+".</td>";
data +="<td><input type='text' id='first_name"+i+"' name='first_name[]'/></td> <td><input type='text' id='last_name"+i+"' name='last_name[]'/></td><td><input type='text' id='tamil"+i+"' name='tamil[]'/></td><td><input type='text' id='english"+i+"' name='english[]'/></td><td><input type='text' id='computer"+i+"' name='computer[]'/></td><td><input type='text' id='total"+i+"' name='total[]'/></td></tr>";
$('table').append(data);
i++;
});
</script>
Also refer demo & tutorial for this dynamically add & remove table rows