As far as I know from the contest guidelines, the contest starts 25th of each month and ends the 25th of the following month. However, I have received my login and password for the contest platform in Jul 12th and it says that the login would expire in July 31, 2011.

So, when do I start trading and when do I end.

Please clarify this for me so that I can enter the contest asap.

Thank you.

The contest starts on the 1st of every month and ends on the 30th/31st of the month. However, the registration is opened in advance - starting from the 25th. When you subscribe, the trading credentials are sent to your email. The contest accounts automatically becomes active on the 1st of the month.

Referring to your situation - if you have joined the contest in July, 12th, you participate in the current contest month (which is July). In order to apply for August, you have to wait until July, 25th.