Site-wide font customization?

This is something I’d asked about in this forum in the past, but only got a partial answer to (part of the question was having to do with changing the font of the pagination links at the bottom of the page – this question was resolved from that post, so this is no longer an issue, although I no longer have pagination links with how my site is formatted anyways) but didn’t quite solve the larger issue I was hoping to get to the bottom of. While I’ve looked at other posts where changing the font throughout your entire blog/site has been addressed, I can’t seem to implement it for myself, and so I was hoping @matt or something else from the team might help.

I’m looking to change the font of all the text on my site to Ubuntu Mono (but would like to know how specifically to change this, if in the future I wanted to change the look to a different font). While topics like these:

…have made clear that this is doable (also, seeing it done on other peoples Write.as blogs), I haven’t figured out the code necessary to make it work on my blog, nor have I been able to pinpoint where exactly the file links I would need for importing custom fonts on fonts.google.com exist, so that (assuming I had the code snippet for my site’s CSS – or JS? – to make this happen in the first place) in the future I might be able to change it again to something else. Also, if I were to change it, would I need to change this for each font type (of the three given styles), be it serif, sans-serif, and monospace? Currently my posts are all in monospace, as you can see if you visit the site @ https://tits.international.

Anyways, I hope this comes across clearly, and that I’ll be able to make this alteration with a little help. If anything is murky in description, I’d be happy to help clarify as best I can.

Thanks!