Sounds like you've got something like cPanel? See screenshot.
You can probably get your heart server address from inserting something like:
<?php echo "Server address: " . $_SERVER['SERVER_ADDR'];?>
into one of your pages.
Now take the address and place it into your cpanel.
I'm no expert on this - I'm assuming a bit here.
I Agree totally. In that picture shows where you enter in the remote host(s). There may be more than one in this situation depending on the isp setup. I have done this setup myself and is very simple. First in the site with mysql like ardave said you will need to enable remote hosts. The first remote host will be %.website_without_database.com
and notice it uses the subdomain %. Remember to replace the domain with your real domain. Then in the below script replace the host (first parameter) with the website that contains your database. Then enter your username and password. Then run the script and follow the next step.
<?php
mysql_connect('website_with_mysql.com','username','password') or die(mysql_error());
For example, if I were doing a remote host to my website it would look something like this (password is different though)
<?php
mysql_connect('cwarn23.net','root','abc987zyx') or die(mysql_error());
Now you will probably see an error. The error will say that it cannot access the database due to some security violation. To solve this copy and past the host name in the message into the box ardave pointed out. Now you should have 2 remote hosts set in your cpanel. Then you may need to run the above …