Hi MelissaRRD,
Welcome to QBCommunity!
Pay events can only be created after a pay run is finalised.
If you have not created any pay events so far, you can start from July 1 by unlocking the pay run, then finalising it again. In the Finalise Pay Run menu, you will see an option to Lodge to the ATO. Simply select that and it will bring you to the Lodge Pay Event screen after the pay run is finalised, which is where you actually send the pay event off to the ATO.
When you send a pay event to the ATO, you report the Year-to-Date figures along with it, so in the case that you have started lodging pay events after July 1, just continue lodging them as usual, without backdating. However I would recommend contacting the ATO to ensure that their Year-to-Date figures are the same as what you have.
Hope this helps!
Bonny