If you event is for public registration, setup registration form and you can share the link to your guests for registration via following steps:
1) Design your registration form (make sure the registration form is switch "ON" for registration)
2) You are not required to import attendees as this is open registration
3) Setup confirmation email template such that your guests will receive confirmation email manually or automatically after they submit registration form. (Please turn on "Auto Email Notification" if you want our system to send confirmation to your guests automatically)
4) Share the registration link out for registration purpose.