I need to get my battery replaced with my iPhone

Schedule an appointment at your Apple Store Genius Bar for that --> https://support.apple.com/iphone/repair/battery-replacement

Do NOT let anyone other than Apple or an actual Apple Authorized Service Provider (BestBuy is one in the US) replace the battery in your iPhone. Only Apple or an Authorized Service Provider have access to genuine Apple Parts.

Please read the reply that has already been posted.