How to access checkbox checked value and use that in email built using C#

<td colspan="4">
<input type="checkbox" name="Yes" id="chkYes" value="" onclick="alert('Do something.');"/><B><FONT size="1" face="Verdana">&nbsp;&nbsp; Yes </FONT></B>&nbsp;
<input type="checkbox" name="No" id="chkNo" value=""/> <B><FONT size="1" face="Verdana">&nbsp;&nbsp;No</FONT></B>
</td>
        emailBody +="<tr>";
        emailBody +="<td align='right' width='10%'><B><FONT face='Verdana' size='1'>Do you have any active MTY billing?</FONT></B></td>";
        emailBody +="<td width='20%'><FONT face='Verdana' size='2'>&nbsp;" + chkValue + "</FONT></td>";             
        emailBody +="</tr>";