I'm not an expert with Word Press nor familiar with PowWeb, but you should never give out your login or password.
If the WP folders are in your root directory, you will also see an index.html file which is the PowWeb page which I see at your site. Most likely they have supplied you with information about setting up a database or they may have done so for you and given you the necessary infomation to configure your Word Press installation. That is done by editing the wp-config-sample.php file which should also be in your root directory.
define('DB_NAME', 'wordpress'); // The name of the database
define('DB_USER', 'username'); // Your MySQL username
define('DB_PASSWORD', 'password'); // ...and password
define('DB_HOST', 'localhost'); // 99% chance you won't need to change this value
Fill those in with the information PowWeb has supplied you with (or the database name they have told you to make. Then save the file as wp-config.php and upload it to the same root directory. Then open http: //YOUR_SITE_NAME/wp-admin/install.php and you should arrive at a login page with admin as your user name and the password which was generated by Word Press.
When you login there you are at the Dashboard and ready to begin writing and configuring it to your heart's content.