This is a Breville instructional video. Pretty similar machine, same principles apply. There is lots of variation and different opinions on smaller detail, but this might be a good starting point.
The grind setting number is a reference which works only for you to compare which setting produced a good / poor result in your machine. Same number setting does not necessarily grind to exactly the same size on someone else's machine, so you need to do some experimenting after watching the video. Grinding finer will increase slightly the time it takes to grind the same 15g of coffee.
Hope that helped.