Never fear! Macros are ez pz. You can just select all the relevant nodes (in your case the x and y random float in range stuff, and the make vector node i guess), right click, and select the create macro option.
Then just nest that inside a loop and youre done!
Macros and functions can be as simple or as complex as you need them to be. You just gotta do a bit of planning of what inputs and outputs you need to most efficiently and flexibly produce the output you need.