lib.php파일에서
// 푸터 부분 출력
function foot() {

global $width, $group, $setup, $_startTime , $_queryTime , $_foot_executived, $_skinTime, $_sessionStart, $_sessionEnd, $_nowConnectStart, $_nowConnectEnd, $_dbTime, $_listCheckTime, $_zbResizeCheck;

if($_foot_executived) return;
$_foot_executived = true;

$maker_file=@file("skin/$setup[skinname]/maker.txt");
if($maker_file[0]) $maker="/ skin by $maker_file[0]";
else $maker = "";

if($setup[skinname]) {
?>
라는 부분을 찾습니다.

그 아래에
<table border=0 cellpadding=0 cellspacing=0 height=20 width=<?=$width?>>
<tr>
<td align=right style=font-family:tahoma,굴림;font-size:8pt;line-height:150%;letter-spacing:0px>
<font style=font-size:7pt>Copyright 1999-<?=date("Y")?></font> <a href=http://www.zeroboard.com target=_blank onfocus=blur()><font style=font-family:tahoma,굴림;font-size:8pt;>Zeroboard</a> <?=$maker?>
</td>
</tr>
</table>

과 같은 것을 넣으시면 됩니다.(건드린 부분이 없으시다면 lib.php만 따로 덮어씌우셔도 됩니다.)

<font style=font-size:7pt>Copyright 1999-<?=date("Y")?></font> <a href=http://www.zeroboard.com target=_blank onfocus=blur()><font style=font-family:tahoma,굴림;font-size:8pt;>Zeroboard</a> <?=$maker?>