To register a new Apple device you need an Apple ID. You can register for a new ID on your iPhone when you first start it up, but I find it much easier to create an Apple ID from the Apple website. If you are on an overseas holiday be careful about using your temporary phone number to sign up for an Apple ID.
An Apple ID is an email address with a password. You can use any email address. It does not need to be an Apple email address. You give Apple your email address, then you need to create a new password that will be used to sign in to Apple. For example, if you have a Google Gmail email address (firstname.lastname@example.org) you can use that email address, and you then create a new password so that your Apple ID is your existing email (email@example.com) with a new password.
Be very careful to not lose your password.
If you lose you password, and you if cannot verify yourself with a phone number or email, you will lose access to all your photos, and everything that is stored with Apple. And you can never get them back.
When you sign up Apple will ask you for an existing email address that you can use as your recovery address and an existing phone number. Make sure you have access to these. Make sure you remember which email address and phone number you used. If you forget your password, and you forget which recovery email and phone you supplied, you will also lose all your data. I have some friends who this happened to. It’s easier than you think! For example, if you go on an overseas holiday, and use a temporary phone number, but use that phone number to sign up to an Apple ID, if you no longer have access to that number, and you forget your password, you are in trouble!
Be very careful with your Apple Password. It’s important.
What you need
An email address (it will be used as a recovery if you forget your password)
A phone number (it will be used as a recovery if you forget your password)
A name and date of birth
A password with an uppercase letter and a symbol
Create your Apple ID
I find Safari web browser more reliable than Chrome to do this.
Select ‘Create your Apple ID’
Type in all the relevant details.
Be sure to save the password!