Help with holes in PCB

A via is a plated through hole with a pad on both sides of the board, and you change sizes in the Inspector.

Maybe you should watch some Fritzing tutorials to pick up more tips, because it has lots of hidden things.

https://www.google.com.au/search?client=opera&q=Fritzing+tutorials&sourceid=opera&ie=UTF-8&oe=UTF-8#q=Fritzing+tutorials&tbm=vid