Multiple rows in a Measure

Hello Community, 

I`m sure this is going to sound like a pretty basic question (and i`m equally sure its going to pretty obvious) but I`m not sure what its called so therefore can`t search effectively for it.

I have come across multiple measures that contain lots of numbered rows of DAX in the measure but i`m unable to do this myself.  What do I need to do to create row 2, and then more numbered rows following - I`m not sure what to hit on my keyboard and this is pretty frustrating.

Thanks in advance!