Use

There are a ton of events that are tracked automatically. To see a full list, check out the Default Events

If you want to track a custom event, you need to:

var analyticsManager = AnalyticsManager.Instance;
var eventData = new Dictionary<string, object>();
eventData.Add("remaining_lives", 2)
analyticsManager.TrackCustomEvent("LostLife", eventData);

For Garbage Collection purposes, if you are sending an event frequently, make sure you recicle the dictionary, and not create a new one every single time you call TrackCustomEvent.

AnalyticsManager _analyticsManager;
Dictionary<string, object>() _eventData = new Dictionary<string, object>();

void Start()
{
    _analyticsManager = AnalyticsManager.Instance;
}

void FrequentlyCalledMethod()
{
    _eventData.Clear();
    _eventData.Add("remaining_lives", 2)
    _analyticsManager.TrackCustomEvent("LostLife", _eventData);
}