If you are a new BT Broadband customer, since October 2022 BT no longer supply an email account to BT Broadband customers or allow customers who were a BT Broadband customer prior to that date, who had not already set up an email account to set one up now.
If the above does not apply you need to log onto your MyBT then go to "Your Products" then Email Manage.
See link
https://www.bt.com/help/email/manage-email-account/account-set-up/how-do-i-create-and-activate-a-new...
