How to use to edit function.php

I have been advised to add a line of code in the functions.php file to resolve an issue with another plugin (TablePress). It was suggested that I could do that by creating a child theme with Child Theme Configurator.

I don’t know much about WP coding or PHP so I am a little bit overwhelmed by all the options in this plugin.

So the question is really:

Can I use the plugin to “add a line” in functions.php? If so, how do I do it?

By the way, just FYI, the code I need to add is:

add_filter( 'tablepress_wp_search_integration', '__return_false' );

This turns off search integration with TablePress.