how to create and use virtual users

Make a Controller Scenario.

yes right. You need to make a controller scenario. You can create a scenario by clicking the RUN LOAD TEST link on the main Load Runner screen (or click on TOOLS and then CREATE CONTROLLER SCENARIO)

Once open, rigth click on the grey area and click ADD GROUP,. then select your script from dick and specify necessary information (like number of users to simulate etc.)

In the scenario schedule, opt for REAL TIME SCHEDULE

I hope this helps.. If you need to talk more, contact me directly or add on IM.

Regards,
Kam