Since you are just beginning, I would suggest that any fine ground dark roast coffee would be a good place to start, but I see that Starbucks has an espresso product and since they are ubiquitous, you might want to start there. OTOH, you could order This from the makers of your stove top device.

Lots of coffee offered in supermarkets offer an espresso grind....start there.

Yeah.....and it's eSpresso.....there is no "X" in the word.

thank you!

I use a Moca pot and I can't grind as fine as an espresso grind. I grind midway between drip (or filter on my grinder) and espresso. If the coffee is too fine the pressure in the boiler can' t force water up through the grounds. Most of it just goes out the vent. I also prefer a medium/light roast because I can taste the fruitiness of the beans. Grocery store coffees (and even Starbucks) don't have fresh roased beans. Around my area there are several vendors selling beans that are under a week old. I would try to find one if you can.

A coffee grinder isn't that much, and I prefer to grind my beans just before putting them into the water for maximum freshness. To me it's worth the extra $30 or so for the grinder

I'm a fan of Lavazza myself