be carefull when you say 'use templates'
you can achieve the functionality of Smarty and such without having to use their system...
template systems work as such in concept
# TEMPLATE FILE
<u>Template File</u>
<b>{{tag_to_replace}}</b>
# PHP FILE
$template_file = 'path/to/file';
$tmpl = new TemaplateObject();
$tmpl->LoadIntoMemory( $template_file );
$tmpl->setReplace( 'tag_to_replace', 'replaced_value' );
$tmpl->parseTemplate();
print $tmpl->parsedOutput();
/// prints :
<u>Template File</u>
<b>replaced_value</b>
behind the scenes these templates run regular expressions to replace every instance of {{tag_to_replace}} with the value you gave. They also have complicated logic in order to allow you to use some if() else() and for() structures.... which is, in essance, another language they wrote on top of PHP, this is not needed. now you need to learn their template language.
I DONT LIKE THESE SYSTEMS:
If this is all you want to do: please use this type, it is similar in output and is much more efficient, as it relies on php to do all the work internally.
# TEMPLATE FILE
<u>Template File</u>
<b><?=$tag_to_replace?></b>
# PHP FILE
$template_file = 'path/to/file';
$tag_to_replace = 'replaced value';
include( $template_file );