The error messages you are getting are referring to the db variables that should be in your connection file. The file should be listed in the connections folder as localhost.php. You must ensure that there is a require once line for this connection on the page. As another test you can do create a new page and apply a recordset to the page. If you can test the page with the recordset on it then you should be able to get this other page to work so long as the connection file is linked properly.
This line should be at the top of the page and it should look like this:
<?php require_once('../Connections/localhost.php'); ?>
Inside of this file you should have all of your information to connect to your db. Please check this out and run a test on a page to confirm the path to the connection file. If your pages links to this file in the same way it should work the same also. Let us know if you have any other problems.