I have another question regarding this subject. If I create a custom module how do I use the templating engine to work with the output of the module? I know this code is bad, but it summarizes what I would like to do. Any help is appreciated as I'm starting to feel dense from not being able to figure this out.

#################################################
module code - mymod.php
#################################################

function mymod_menu($may_cache) {
$items = array();
$items[] = array('path' => 'mymod_view',
'title' => t('mymod_view'),
'callback' => 'mymod_foo',
'type' => MENU_LOCAL_TASK,
'access' => user_access('view mymod'),
'weight' => 0,
);
return $items;
}

function mymod_foo() {
$data = array('foo' => 'bar');
return $data;
}

#################################################
template.php code
#################################################

function phptemplate_mymod_foo() {
return _phptemplate_callback('mymod_foo');
}

#################################################
mymod_foo.tpl.php
#################################################

<h1>I want to output value of $data['foo'] here</h1>