The Databricks documentation provides many ways for you to get up to speed on the platform.
We have Getting Started tutorials for Databricks and Apache Spark:
Specific areas within the Databricks documentation contain introductory material:
For Apache Spark frequently asked questions, see the Apache Spark FAQ.
The Databricks training organization, Databricks Academy, offers many self-paced and instructor-led training courses, from Apache Spark basics, to courses that focus on specific task categories such as ETL for data engineers and machine learning for data scientists.