Observe that the Driver Script is Loaded. Clicking on Load will reload the script.
Further down the tree-view under Virtual User select Options and select "2" for the number of Virtual Users, click OK.
Click on Create and the Virtual Users will be created and waiting to run in an idle status. (Clicking run first will run both Create and Run Immediately).
Double-click on Run - you can now observe the Virtual Users running a workload against the database. When ready press the red stop button to stop the workload.