[EnIgMa1234]

k first of all if your using plugins hooks are used to display the code on pages e.g forumhome_compete will execute at the bottom of the index.php file.

If your adding code, you will be using member_***

Next, you dont need to connect to the database, it is done automatically. Also you dont need the opening php tag or the closing one.

Finally I taken a bit of your code and changed it around to be more vbulletin compatible

PHP Code:

$counter = 0;

    // Lets get the Recent Reviews
        $queryz = $vbulletin->db->query_read("SELECT 
  rp_products.title,
  rp_reviews.username,
  rp_reviews.userid,
  rp_reviews.review,
  rp_reviews.cat,
  rp_reviews.product,
  rp_products.bigimage,
  rp_products.cat,
  rp_products.userid
FROM " . TABLE_PREFIX . "
 rp_reviews
 INNER JOIN rp_products ON (rp_reviews.product=rp_products.id)
WHERE
  (rp_reviews.review IS NOT NULL) AND 
  (rp_products.approved = 1) AND
  (rp_reviews.userid = {$vbulletin->GPC['userid']})
ORDER BY
  rp_reviews.`date` DESC LIMIT 5");

// Printing results in HTML
echo "<div align=\"center\">\n";
echo "<table width=\"100%\">\n";

while ($row = $vbulletin->db->fetch_array($queryz)) { 

   $title = $row['title']; 
   $review = $row['review']; 
   $username = $row['username'];
   $product = $row['product'];
   $bigimage = $row['bigimage'];
   $cat = $row['cat'];
} 


Also it's better to use templates instead of echoing html. Chec the articles section for more help.

Hope that helps.