php include with CI

[eluser]defrey74[/eluser]
Here is what i am trying to do?

In a normal php app i will use the following:
<?php include('lib/file.php'); ?>

I just want to be able to do the same in CI:
Might look like something like this:

<?=base_url()?>lib/file.php>
My question is Where do i put the include?

Thanks

Fred