Really good video about brewing your cup using your espresso machine link
Notes from this video
Grinding
Dark roast works best with a coarser grind
Light roast works best with a finer grind
Make grind Finer if coffee comes out too fast; adjust Coarser if comes out too slowly
Dose should be the most ground coffee you can put in the filter basket without seeing an imprint of the screen after drawing the espresso
Adjust Grind, not Dose.
Adjust dose to get more or less espresso out.
Timing. You should get 2:1 espresso out in 25-30 seconds. For a 18g dose, you should get 36g espresso out in 25-30 seconds.
Temperature of water going into filter to be 93-95 C