How add custom font

I use the free version of Himalayas, and I’m aware 500+ Google fonts are not included as in the premium version. Does that mean that changing the fonts is something you can do without touching the code in the premium version, while with the free version you have to edit the header.php and style.css? Or is it simply impossible to change the fonts in the free version? Because I’ve tried and it’s not working.

I’ve followed this guide on how to get a google font on your site but with no success. I made the changes in the header.php and style.css of my child theme, because I shouldn’t need to edit the mother theme, should I?

Anyone who knows what I’m doing wrong? Grateful for any help!