hi frnd,
you can use below example for merge 2 cell:
For HTML
<table>
<tr>
<td colspan="2">
merge Cell Display header here
</td>
</tr>
<tr>
<td>Cell 1</td>
<td> Cell2</td>
</tr>
</table>
ColSpan: if you want to merge N Cells then Colspan Attribute value = N ie. for merge 10 cells, ColSpan attribute value = 10.
For ASP.net Table Control
<asp:table runat="server" xmlns:asp="#unknown">
<asp:tablerow>
<asp:tablecell columnspan="2">
Merge cell : display Header here
</asp:tablecell>
</asp:tablerow>
<asp:tablerow>
<asp:tablecell>Cell1</asp:tablecell>
<asp:tablecell>Cell2</asp:tablecell>
</asp:tablerow>
</asp:table>
here we have
ColumnSpan attribute for merge the cells