Go through one of the guides to "Add your own data".
You can test that things work by querying the resulting dataset table.
Configure a Google Service Account
A Google service account is a special kind of account that can be used by programs to access Google resources like a BigQuery data warehouse. You will use this service account to connect DataCamp Workspace to your BigQuery warehouse.
To set up a new Google Service Account, please refer to this excellent guide. At the end of it, you'll have the JSON credentials file that you can use to set up the BigQuery connection in Workspace.
Set up a Google BigQuery connection
When inside a workspace, click View > Databases, then click the + icon and follow the on-screen instructions. Upload the Service Account JSON and hit "Connect".