The tickets will be emailed to the registrant as a pdf attachment after they complete the event registration form. They will then be able to print the ticket and take it with them to the event or show the electronic pdf version from their mobile device. Only the registrant will receive the tickets. It will be the registrant's responsibility to share the tickets with their guests. You will always be able to look up information about a registrant or guests from the Event - Details grid or Event Attendance grid if a guest arrives without their tickets.
You can resend a registrant's tickets from the Events Grid in Workspace > Events > Events by clicking on the solid blue Envelope Icon on the far left side of the grid. Do not confuse this with the Mail Merge envelope icon, which is not solid blue and is in it's own column under Mail Merge. You can also reprint the tickets by clicking on the Printer Icon. This will open a new browser tab with the tickets in a pdf file.
You can resend tickets to up to 100 registrants at a time by using the Actions menu, and clicking on Resend Tickets. If you have more than 100 registrants at your event, you will need to filter your list into groups of 100 or less. You could do this by filtering by ticket level or date range to to get 100 or fewer registrants per resend batch.