[Gambas-user] Groups in Report

[Roki]

Ok guys! I have a question about creating a group in gb.report.
I want to show data for the vehicles, which I took from a database and 
grouped according to their type.
For example :
  ----- Cars
             --- Licence plate | Make        | Model  | sm3   | kW
             --- ST-5555AB     | Mercedes | C220   | 1989  | 88
             and so on...
----- Truck
             --- ST-1111AC     | IVECO      |  240L   | 4500   | 102
             and so on...

I successfully created a report with the data, but stuck with creating 
groups.
Is there any small example, which will help ???