You will need to pass your products/services through a Smarty variable.
In your PHP file:
global $smarty;
$products = "Query goes here";
$smarty->assign("products", $products);
Then in your .tpl file you can access it as following, assuming it's an array:
{foreach $products as $product}
<p>{$product.name}</p>
{/foreach}
This is really basic knowledge though. You may want to consider re-reading the basics of templating.