Hi,
From Setup, go to Build, and click the drop-down arrow next to Develop. Click External Data Sources and select New External Data Source.
Enter OrderDB for External Data Source and name the data source OrderDB, and select Salesforce Connect: OData 2.0 as the type.
Enter https://orderdb.herokuapp.com/orders.svc as the URL. Leave the other fields with their default values, and click Save.
On the next screen, click Validate and Sync. Salesforce Connect retrieves the schema from the external system.
Select both the Orders and OrderDetails tables, and click Sync.