Add the red lines to accounts.php
Fileserve
$premium_acc["fileserve_com"] = array('user' => 'your username', 'pass' => 'your password');
Filesonic
$premium_acc["filesonic_com"] = array('user' => 'your username', 'pass' => 'your password');
Change 'your username' and 'your password' with your username ans password