How to receive messages on my new iPhone?

Recently I upgraded from an iPhone 6s to an iPhone 8 plus and my previous phone has been still receiving my messages not my new phone and when I send texts from my new phone it sends from Apple ID not my phone number. I tried fixing it by going to my new phone settings and looking under 'Send & Receive' and I saw that only my Apple ID email is listed not my phone number. How do I fix this problem?