Where to place php loops, get_posts ?

Help me, please, because I think I’m going crazy.

I’ve created a massive amount of custom posts on my website and the time has come to create some listings, so that people can actually access these posts/pages.

I’ve looked everywhere and the only solution seems to be working with “the loop” and “get_posts”. I see heaps of php examples everywhere, but nowhere can I find an instruction on how to actually introduce them on my website. In other words: how do I get these php-codes on my website? What do I do? I can’t seem to find an instruction for newbies anywhere, they all start with:

<?php // The Query $the_query = etc.

But when I put this on a page or post, nothing happens (obviously, I hear you sigh).

Please heeeeelpppp!