Show results in content area

Ok, my site actually depends on the this day in history module. Every day, it displays the birthdays of famous people. It all works great. But I do have a couple of issues. I added an advanced search option. I want my visitors to be able to select a date, hit "zoeken" and then my site must show all of the birthdays of that particulary day. This must be shown in the content area.

Here is what i have done so far. I created a block called "zoekdatum" and put this code in it:

// variables
$maand = $_POST["MAAND"];
$dag = $_POST["DAG"];

// selectieformuliertje
$mijnForm = '
<form method="post" action="/site//modules/birthdays/sdate.php" target = "content">
<select name="DAG" size="1">
<option value="1">1</option>
...
...
<option value="31">31</option>
</select>

<select name="MAAND" size="1">
<option value="1">Januari</option>
...
...
<option value="12">December</option>
</select>

<input type="submit" value="Zoeken" name="Klik"><br />
</form>';
echo $mijnForm;

This is the sdate.php-file:

// variables
$server = "localhost";
$database = "***";
$db_user = "***";
$db_pass = "***";
$maand = $_POST["MAAND"];
$dag = $_POST["DAG"];

// connect to the mysql server
$link = mysql_connect($server, $db_user, $db_pass)
or die ("Could not connect to mysql because ".mysql_error());

// select the database
mysql_select_db($database)
or die ("Could not select database because ".mysql_error());

$rows = 200;
// read data from database
$result = mysql_query("select a.nid, a.body, b.year, b.month, b.day FROM node_revisions as a LEFT JOIN thisdayinhistory b ON (a.nid = b.nid) where month='$maand' and day='$dag' ORDER by b.year asc limit $rows", $link)
or die ("Could not read data because ".mysql_error());

// print the data 

echo "Jarig op  ", $dag, " - ", $maand, "<br><br>";
if (mysql_num_rows($result)) {
while ($qry = mysql_fetch_array($result)) {
echo $qry[year], ": ", $qry[body] ;
echo "<br>";
}
}

This kinda works. When I hit the "Zoeken"- button, the results are shown on a new tab (Firefox). IE opens a new window. Also, there are strange characters shown: é, í, á are shown as � (only in Firefox; IE shows them correctly).

What I want is that when I hit the "zoeken"- button, my site shows the results in the content area, without the �-characters and with the selected theme. But I'm stuck! Don't know how to fix these issues.
Can someone please help me out? My site is at www.vandaagjarig.com (Drupal 5.7; PHP 5.2.6; MYSQL 5.0.32)

Btw. I am totally not into PHP coding. I created the block and the sdate.php I mentioned using good ol' Google. (It took me a couple of days though!)