You can record an observation with iNaturalist in a number of ways, including on their website and using your iPhone or Android.
Using their website, adding an observation with iNaturalist is similar to the Record a Sighting function of the ALA.
First, click on Add observations.
Then, add your image/s.
You can then add the species name if you know it. iNaturalist may make some species suggestions that you can choose from.
You can add some more information about the observation if you like. Then click Submit observation.
That observation will then appear at the top of the list of Your observations.
Once your observation has been verified by another user, Needs ID will change to Research Grade.
A clear guide on the process of adding observations with iNaturalist is available here: https://www.inaturalist.org/pages/getting+started