You have to add a line and port the number from Straight Talk. You might have to purchase a compatible phone if the you don't have one.
I'm most definitely NOT a VZW employee. If a post answered your question, please mark it as the answer.
Are you wanting to bring an extra/new line to Verizon or just the phone? The phone may not be compatible even though ST uses Verizon towers, if the phone is a GSM and your phone used the ATT towers. Otherwise, if it is just the number, you just go through the shopping process online and port your number in, or do the same in-store.