To to add a new occurrence from either the home screen or login screen you need to know the PIN and Token number for your occurrence. This can be found on the Get App tab of the Mobile event capture tab, as described in "How do I find my token or pin number?", or if you're a Student Ambassador, this should have been provided to you.
N.B. The above screen assumes you haven't yet logged in - the User field is not present once you're logged in.
Enter your username, if required, the occurrence token, and PIN, then click "Authorise". after a few moments the new occurrence will appear in the list.
Updating Occurrences
Alternatively you can just update the occurrence.
Go the the Admin area where you will see the three icons in the green banner (top right).
Tap the cog icon on the right.
In the Settings list, tap 'Update Occurrences'.
This will pull down all the updates. This will take a little while and you'll see when it's orange it's updating and goes black when it's complete.