how and where am I supposed to pay my first bill?
If you haven't registered on My Verizon yet, you need to do so, as your My Verizon account is the most convenient way to set up automatic payments or make manual payments. There are other options such as the one-time bill pay site or visiting a payment location (details below).
Registering on My Verizon:
https://www.verizon.com/onesearch/search?q=register+on+my+verizon&ES=shop&src=wireless
Paying your bill:
https://www.verizon.com/onesearch/search?q=pay%20bill&ES=shop&src=wireless