Creating a dependent list

Hi guys,

First time posting - relative newbie!

I just wanted to ask how to solve the following:

I would like to have a yes or no drop-down so if someone selects yes the following rows should populate with something like, "item 1", "item 2" and so on. Should the person select no from the drop down, the row below only populates once with "item". 

How would I go about doing this?

Ty~