How can I change my Apple ID

Log in with your actual Apple ID from this link and there you can change your Apple ID to get a new one , you shoukx log out from the AppStore, FaceTime iMessage etc etc , make sure to do a iCloud backup first

https://appleid.apple.com

See the Apple Support article(s) below.

Apple ID Name Change.  * 

Make sure you turn off Find My Phone before signing out of the old ID. Once signed out and Find My Phone is off, then sign in with the new ID, then turn Find My Phone back on.

 What to do after you change your Apple ID or password - Apple Support