How do I make a second gmail account?

Click your profile picture at the top right of Gmail, Add another account, then Create account. You don't need to log out of the first one, and afterwards you can flip between them from that same picture. You can use your first address as the recovery email for the new one. Google may ask for a phone number, and you can reuse the same number, though there's a limit on how many accounts one number can verify.