Help finding “add post” location

I was hoping someone could help me out.

I’m looking to integrate WordPress onto my site, I have it skinned great. Where I’m stuck is that I have other content I add (non-WP). On the home page, I’d like to display the 5 most recent items from any category, and so each time an item is inserted, I also add the item to an additional table with its timestamp. Then I simply take the 5 most recent from there to display.

What I’m trying to figure out right now is where I can add this into the WP code so each time a WP post is made or deleted, it will add to the other table. Right now, I have code inserted into the “case ‘post’:” in the “wp-admin/post.php” file. It doesn’t seem to work in the least.

Any help would be appriciated.