You will find the basic definition for espresso in this official document from the INEI: Definition Espresso

Beans and grinder adjustment

Click here to read the article about grinders and beans.

Quickly heat-up

The portafilter with basket must be inserted when starting up.
Cups can be warmed with the hot water valve before the first extraction.

Tamping

It does not need to be tamped with a lot of pressure. What’s important is that the coffee is evenly distributed and has a smooth surface. Before tamping try knocking against the filter to get an even better distribution.

Double filter

For beginners it’s easier to start working with the double portafilter.

Frothing

First of all, leave some room in your milk jug for the froth (e.g. fill a 0.6 l jug with only 0.3 l of milk). You should hold the steam wand diagonally in the milk, just below the surface — that ’s simple with the Xenia’s steam wand since it isn’t stiff. The aim is to hear only a slight sipping sound to mix the air into the milk. The milk will start turning in the jug. Since the volume will increase, you will need to start lifting the steam wand (lowering the jug) after some seconds. When the jug becomes so hot that you prefer to remove your hands, do that — you’re finished.
Click here for more tips (german text).