Once you receive your SIM card, check here to begin your activation
Here is info from part 3 of the above link. It descibes how to choose your phone number.
When creating your plan, you’ll need to choose your phone number. There are three ways to select your phone number:
(Your number must be active to transfer from another provider.) Learn how
2. Ask Fizz to give you a new number. Learn how
3. Find a number by entering the last 4 digits. (This option has a one-time $1 fee.) Learn how
Your phone area code is linked to the postal address associated with your Fizz account.