Quick Question About Subpages In Custom Pages

[The-Ensemble]

I can't seem to get a answer for this.
What needs to be put in where it says

// Block of code #1 & 2

Is there something specific or do I leave those there?

I'm new to php and the subpages Is something I REALLY want to use.


Creating "Subpages"

If you want to create "subpages" within your custom page, simply wrap blocks of code with the following structure:

if ($_REQUEST['do'] == 'test')
{
// Block of code #1
}

if ($_REQUEST['do'] == 'test2')
{
// Block of code #2
}



ETA:
Is the code I need something like this?
if ($_REQUEST['do'] == 'xxx')
{
eval('print_output("' . fetch_template('TEMPLATE_XXX') . '");');
}