Creating custom font style for buttons and headers

Hi there,

I would like to use a custom font style on specific buttons and headers. I have input the css for the font location but need to know next steps. Not sure of the class names for buttons or two headers (see image) See CSS below:

//ADDING myfriend FONT//
@font-face {
    font-family: 'myfriend';
       src: url('https://static1.squarespace.com/static/5dbb8e5c55a40158cc4627af/t/5e0e9aead2e16f330f9816b1/1578015466865/myfriend.ttf');
  }

Difficult to determine CSS class with only screenshot.

You should share link to your site to check.