How to setup IP range address's

Hi
I would like to know how to make an ip range for these address's

192.168.1.90- 192.168.1.99
192.168.1.80 - 192.168.1.89

I keep seeing stuff like 192.168.1.1/30 and I have seen it explained but it still doesn't make any sense to me.

any help would be greatly appreciated