<table id="table">
    <tr>
        <td>Cellule 0</td>
        <td>Cellule 1</td>
    </tr>
</table>
<input type="button" value="Ajouter une ligne" onclick="AddRow()" >

<script type="text/javascript">
function AddRow(){
    var newRow = document.getElementById('table').insertRow(-1);
    var newCell = newRow.insertCell(0);
    newCell.innerHTML = '[nouvelle cellule 0]';
    newCell = newRow.insertCell(1);
    newCell.innerHTML = '[nouvelle cellule 1]';
}
</script>

<table>
    <tr>
        <td id="cel">Bonjour</td>
    </tr>
</table>

document.getElementById('cel').innerHTML = "Au revoir";

<div style="height:200px;width:20px;overflow:auto;float:left;" onscroll="document.getElementById('tableau').scrollTop=this.scrollTop;">
</div>
<div id="tableau" style="height:200px;overflow:hidden;width:80%;">
<table border="1" width="100%">
</table>
</div>