okay, in that script there's this bit of code
if(isset($days[$day]) and is_array($days[$day])){
@list($link, $classes, $content) = $days[$day];
if(is_null($content)) $content = $day;
$calendar .= '<td'.($classes ? ' class="'.htmlspecialchars($classes).'">' : '>').
($link ? '<a href="'.htmlspecialchars($link).'">'.$content.'</a>' : $content).'</td>';
}
else $calendar .= "<td>$day</td>";
inside the IF statement is the code for each of the days that have an event, and in the ELSE part of the statement are the days that have no event attached to them.. so if u do something like this
if(isset($days[$day]) and is_array($days[$day])){
$calendar .= "<td>$day</td>";
}
else $calendar .= "<td><a href='link.html'>$day</td>";
all the dates that have events will have no link, an the ones that have no event will have one..