I assume that you mean you got the ticket itself, and then lost it. If so, I think you will just have to wait until you either get another notice, or hear from a collection agency. Without the ticket number, it is unlikely that contacting the authority directly will be of much help. I'm sure they process thousands of tickets - they would need the ticket number to know which one is yours.
You may not get a second notice. It may or may not be sent to a collection agency. If it is, then you'll have to pay all the extra fees and such. If it is not, consider yourself lucky and don't worry about it.
Note - if all you got so far is the notice from your rental agency, you will have to wait to get the actual ticket in order to pay it. The rental agency may notify you that they got a request from the authority to get your contact information and what the infraction was, but they do not handle the actual ticket.