So if you've got an S3 bucket with your data in it, the first thing you'll need to do is connect it to a Databricks workspace to grant access. Then you can start querying the contents of the bucket from notebooks (or running jobs) by using clusters (compute resources) within the Databricks workspace to execute commands.
Here's a guide on the docs site that walks through the process to connect a bucket: https://docs.databricks.com/data/data-sources/aws/amazon-s3.html
Although it shares several options, I'd recommend using instance profiles and mounting via DBFS for simplicity.
