Although I have not registered for the stock game by CIMB, I'm assuming the trading platform/interface used by the game is the same as CIMB's iTrade online platform which is used by traders for real transactions.

If this is the case, go to CIMB website and click the link to it's iTrade website or this link iTrade. Click the 'DEMOS' tab on the top and it will show you how to use the platform and explain what each function or button will do. This is like a training or tutorial for their platform. Most online trading platform has some form of tutorial so their users don't get confused and make the most of what it has to offer.

Good luck and never stop learning and reading once you've mastered how to use the platform. Stock markets are more than just buy and sell.