The MySQL service on Yahoo! WebHosting must be activated using the link you will find on your control panel. All you do is enter a login name (that need not be your normal Yahoo! login name) and password (which may also be different from your Yahoo! account password). Then, I strongly recommend you install the administration package. After that you have your own database server. You may define any number of databases to hold any kind of information that you may want to index, search, or process in some way. The forum on this web site uses a MySQL database. The code is the phpBB package. It was pretty easy to install - just unzip the phpBB package on my local system then FTP the entire directory tree to my web site. (There are a few other steps. Read the manual.)

• The phpMyAdmin package is your friend. If you haven't installed it yet, use this link. Learn how to use it.
• If you install the phpBB package you will be asked for the name of the database into which phpBB will store its data. You must create that database first. The simplest way to do that is via phpMyAdmin.
• I use an automatic header on my PHP pages so I put a function there that connects to my database. That code can't be seen by browser "View Source" or by my "Show Me How" link.