You might want to try using $row['fieldname'] in your table where fieldname is whichever field you want the value listed for.
<?
echo ;
$query = "select * from tablename where CatID = $_GET[CatID] ";
$result = mysql_query($query);
$row = mysql_fetch_assoc ($result);
echo "<tr><th><font size=6 color=blue>".$row['fieldname']."</FONT></TH></TR>";
?>
It looks like what your code is printing up would be "resource result #1" or something similar (it's been a while). You are asking for the mysql_query and not the mysql_fetch_assoc info