Where in to place the php code of a plugin?

[theet]

I'm new to use GetSimple and it looks good!

I have tried to use for example the I18N search plugin and when I place te
(% search %) code on a page, that will be no problem.

But: where, in what file I have to place te php code?
For example the one which shows on the explanation:

PHP Code:

<?php get_search_form(array('slug'=>'search', 'showTags'=>0)); ?>