Help list/menu update fields

I am trying to update 3 field when I pick field from List/menu please help how to do this
code below

<select name="LookupLeadNo" id="LookupLeadNo">
<?php
do {
?>
<option value="<?php echo $row_fmLeads['LeadNo']?>"<?php if (!(strcmp($row_fmLeads['LeadNo'], $row_fmcustomer['LeadNo']))) {echo "selected=\"selected\"";} ?>><?php echo $row_fmLeads['Last Name']?></option>
<?php
} while ($row_fmLeads = mysql_fetch_assoc($fmLeads));
$rows = mysql_num_rows($fmLeads);
if($rows > 0) {
mysql_data_seek($fmLeads, 0);
$row_fmLeads = mysql_fetch_assoc($fmLeads);
}
?>
</select>