So ...

Upon activation, go to Settings => Inline Related Posts. You'll see this ...

... and you need to check the "Active" checkbox to display the available plugin settings.

Which are self explanatory ... You can define the text for your call to action and you can select a theme (with a real-time preview) to customize the appearance of how the related posts will appear in your articles. There are two free themes, "Minimalist" and "Shock" ...

And below, you'll see an option that will allow you to insert inline related posts into existing posts. You can define how many links you want to add in each post and the number of words displayed between two related post links:

OK. Now let's see the magic ...