How do I Create a group email on my Apple phone?

Groups are actually managed via the Contacts.app

You can create a Group in Contacts, and add any contacts into that group.

Then, in Mail.app, you can enter the group name in the To:, CC:, or BCC: field and it will pull up all the relevant contacts' email addresses.

Note the addresses will be populated individually, so use the BCC: field if you don't want to advertise everyone'e email address to the entire list.

Open a new email and type one person to add, then keep adding additional email addresses until you've added all the people you want to add. Or as Camelot suggests, you can create a group in Contacts, which may be easier for you. If I only have a few people I want to send an email to, I'll just add them individually when I start a new email.