plet9090 on "Connecting MySQL with php code in Wordpress"

I am trying to follow this tutorial:
https://developers.google.com/maps/articles/phpsqlinfo_v3

I have the map placed on my page, but I am trying to figure out where I need to place the .php code that inserts a row into my database? Also, where do I place the code that includes my username, password, and database name?

I tried placing these as separate php files in my themes directory, but this did not work.

Any suggestions?

Thanks!