The data handling, or the Data Abstraction Layer (DAL), can be an overwhelming topic. Yet, if you know the right start, it will be fairly easy to deal with.
Hence, here are some good starting topics:
{% page-ref page="add-custom-complex-data.md" %}
{% page-ref page="reading-data.md" %}
{% page-ref page="writing-data.md" %}
Also, listening to events of the DAL will come in handy for sure, so here's that:
{% page-ref page="using-database-events.md" %}