my family shares an icloud account, how do you pick different numbers to use in icloud

If you mean different numbers as in Phone numbers, each device (iPhone) would need a separate iCloud account.

fmterrell wrote:

my family shares an icloud account

That's not a good practice. As ssschmidt suggests, you need to have separate accounts. To get everyone set up with their own accounts, see the instructions in: How to Stop Sharing an Apple ID.

(Note that I am affiliated with that site, and some pages contain ads).