Hello Anjum,
The tunnel example is available as a PDF in the software. Help > Online QuickStart Guide>Generative Components QuickStart Guide (PDF).
There is not an on-line course for this guide. It is a self-paced tutorial. (Edited by me, Paul, on 9/1/2016!)
What Steve refers to is a Special Interest Group (SIG) session recording for May 2015 and you can find it here:
AECOsim Building Designer Special Interest Group the first one in the list: 2015-05 (May) AECOsim Building Designer SIG - Generative Components with Design
There is also a Generative Components forum here in the communities:
If you need help with any steps or exercises in the QuickStart tunnel example you might post there.
We have the AECOsim/GC QuickStart learning path in the AECOsim LEARN server page. There is a Live course for this on the schedule for the week of September 12.:
(Updated by me, Paul, on 9/1/2016)
Refer to Mary's post on the updated GC QuickStart session.
Thanks
Paul