If you want to use wordpress as a CMS or if you want to create some custom functions for some pages you should create a custom page template. Is very easy to create a custom page template and is very useful. Just create a empty .php page. Paste there the following code:

/*
Template Name: name
*/

After you’ve saved this page you can activate it from dashboard > pages (edit a available page). On the right side you will see the “attributes” spot and go to the “template”. Select there the page that you’ve created.

In this new page you can create new functions very easy and you can control them from wordpress.