<table id="tb1" runat="server">
<tr visible="false" id="tr1" runat="server"><td>One</td></tr>
<tr visible="false" id="tr2" runat="server"><td>Two</td></tr>
<tr visible="false" id="tr3" runat="server"><td>Three</td></tr>
<tr visible="false" id="tr4" runat="server"><td>Four</td></tr>
<tr visible="false" id="tr5" runat="server"><td>Five</td></tr>
</table>
Say all of them are invisible
Then I have a button to make them visible one by one, so if row 1 is invisible and I press the button then row 1 should be visible, if I press it again it sees that row 1 is already visible then it makes row 2 visible and so it goes on and on and on.