go to rapidleech/configs/ open config.php, find this and add ur username and pass
$premium_acc = array();
### Remove '//' from the beginning and enter your username and password for enable premium account ###
//$premium_acc["rs_com"] = array('user' => 'UR LOGIN HERE', 'pass' => 'UR PASS HERE');
don't forget to remove the '//' in the beginning //$premium_acc
PS: this one is for rapidshare, other hosts are in the same file, look them up in there.