Please help me to get started - eviltoast

Hello!

I recently got a new espresso machine (a Breville Barista Express if that helps at all), and I have no idea how to get started picking espresso beans. I think I’d like a milder, darker roast for either lattes / cappuccinos but also good for drinking straight.

Where do I even go about finding a good bag of beans? Are there any recommended sites? Do you just go to your grocery store?

Any other advice for a brand-new first timer?

Any help is greatly appreciated!