While you can find "espresso" labeled beans at the grocery market or on the shelf at Starbucks, there really isn't any one "espresso" bean, but rather an espresso grind. You can make an espresso with any type of coffee bean, roasted any way, flavored in any fashion and blended to any taste. However, as espresso is a small concentrated amount of pressure or steam brewed coffee, the grounds must be as finely ground as possible in order to extract the full bodied flavor that makes an espresso shot a shot.
Grind your beans as finely as possible. If you have a high-powered coffee grinder at home, then you know what to do. If you do not have a machine that grinds to a fine dust, you will need to find one that does. Either grind the beans yourself in the machine at the location where you purchase them, or have your barista grind a bag for you. Unfortunately, Starbucks will not grind an already opened bag, so if you have an opened bag of whole beans, take it to a locally owned coffee shop.
Set up your espresso machine or stove top espresso pot, sometimes known as an Italian espresso pot. Real "espresso" machines use mechanical pressure to create the espresso, while others, including the Italian method, use steam pressure. Steam pressure is a much lighter force than mechanical pressure, however a perfect shot can still be created nonetheless. Make sure both devices are clean before beginning.
Distribute the grounds. If using an espresso machine, fill the basket with grounds and forcefully "tamp" (press) the grounds in tightly. If using stove top method, fill the base with water (1/4 cup or up to the fill line) and fill the basket with grounds. Do not pack in the grounds, they must remain loose to allow the steam to get through.
Fill the espresso machine with water according to the manufacturers directions (all machines vary), attach the basket to the machine and turn it on. The shot will be created and timed for you. Sweet shots will take about 17 seconds, while more bold and bitter shots will take up to 25 seconds. For the stove top pot, place it above a burner set on high. Wait for the water to boil and push the steam through the basket. The steaming process should take 30 to 50 seconds once the water has reached boiling. Open the lid to see if all the liquid has come through. Remove from the burner.
Pour the shots into small espresso cups. Each espresso should be between 1 to 2 ounces. When done properly, there should be a layer of rich brown foam on the top, this is known as the créma, and is a marker of a job well done. Serve the shots with plenty of sugar, or enjoy it au-naturel.