OK. This has probably been asked quite a few times, but here it is again. Everything I find on the web is on how to create a custom template for category, which I don't want, and the rest doesn't work. I want to create a custom template for single post, to have plain and simple selection of templates available. One of the blog posts said
locate the single.php and make a copy and call it something like single-newspost.php
Which I did. And then, I should make a php statement like this one
<?php /* Single Post Template:News Post */ ?>
Which I also did. But it didn't work. My guess is- there must also be something in the functions.php , but my knowledge is very limited.