Oliver,
You came to the right place. Some essential things to know:
PHP is a "script" language. Scripts are uploaded to your site, just like standard HTML documents. Basically, PHP runs 'behind" HTML. (Pre-Hypertext Processing) The programming in PHP determines what is output to HTML.
MySQL databases are a commonly featured service of web hosts. Basically, it's a storage point for your program data. Similar to Excel, you have a database name, table name, and field names with field values. Unlike Excel, however, you have a hostname, username, and password for connecting via the internet. All of ListMail's data is stored in a MySQL database. You can delete all of your ListMail files and as long as your database remains your data is still there. You would simply need to re-upload ListMail to your host and set up config.php again to continue where you left off.
config.php comes in the ZIP named config.php.txt for ease of editing. Open up the file in Notepad and note the following lines:
// Required is your database information, the host should normally be left at the
// setting, 'localhost', but not always. Check with your host if it doesn't work.
// Enter your MySQL Information!
$sqlhost = 'localhost';
$sqluser = 'YOUR_USERNAME';
$sqlpass = 'YOUR_PASSWORD';
$sqldb = 'YOUR_DATABASE';
This is a PHP script file. Be careful not to modify anything except the values of the variables. The hostname will usually be localhost unless your host states otherwise. The values for database (YOUR_DATABASE), username (YOUR_USERNAME), and password (YOUR_PASSWORD), can usually be created in your hosting control panel (where you set up mail accounts, etc). Look for a "Databases" or "MySQL" section. Create a database, username, and password, then make sure the user has access to the database. If your control panel does not feature a "Databases" or "MySQL" section, you may need to contact your host to have this service enabled.
Once modified to contain the correct information,
Save As.. the file as
config.php, removing the distribution
.txt file extension.
Please let me know if I can be of further assistance!