How do I sell anything to an event member

Go to Main->View/Change Event->Members Tab for the event in question.

Select the member in the member list. Choose New Ticket from the drop down menu

Sell the item on this ticket.

It's important to make sure the ticket you use is attached to the event. You can confirm this by making sure the correct event is shown at the top of the ticket.. Evens are assigned automatically when the ticket is created from within the event.