The UI guides you through the steps: you browse the typefaces, click on ones you like to add it to your shopping cart of sorts (keeping in mind each adds a smidgin to download time), click "Use" - if you need bold, you have to select that as a variant specifically (and it will increase download). After that, add the css link to your header and access it in your own css.
Excellent!(Sorry for all the "quick hits" as of late... especially for stuff that many people already know about. But I post this stuff just in case people hadn't seen 'em, and as notes for my future self...)