Create a node type that acts like a PHP page? Drupal 7.24, fresh installation

I'm fairly new to Drupal and I'm trying to figure out if it's possible to create a node type that acts like a PHP page. I have a code library that needs certain files required once in a node type that displays output.

I've tried using Full HTML and also created a new text format that had all vanilla Drupal options unchecked and the PHP snippets do not function.

I'm sure I'm mixing up terms and I hope you understand what I'm going for, like I said I'm fairly new. Do I need to look for a different text format?

Thanks for your time, and Happy New Year!
First, you will need to enable the "PHP filter" core module in admin/modules.  I think you did.

Then, you'll need to configure the newly added text format in admin/config/content/formats and assign some role to that text format.  Note that you can also do this from admin/people/permissions.

Useless to say you'll need to be very conservative here and only allow this text format to - very - trusted users (roles).

Finally, in your node content, select the "PHP code" text format and type your code (including  tags).