"A journey of a thousand miles begins with a single step." --  Confucius
This  site is attempting to provide you with resources to assist you in achieving a successful HSC result. As Confucius is suggesting, just start, set a goal, achieve that goal and then set a new challenge for your study.
If you have not previously had sound study habits, then perhaps a goal that you could set is to set aside one hour each night for a subject to study. Use the study schedule provided to create a study plan. This may mean that you review the most recent class work, to reinforce your understanding. The completion of an activity that may be found in the appropriate Study Room, would be a fine inclusion as a learning component of the study hour.
After a five weeks increase the schedule to include two subjects over a two hour period as your new challenge. You will be surprised at how confident you will become with each subject. 
The link "How to study for your HSC" is specifically about preparation techniques and will provide you with a wealth of information that you can adapt to suit your learning style.
Visit the Study Rooms 2011-2012 found in the sidebar. These rooms provide a range of subject specific resources.
A good strategy for you to achieve the best HSC result that you are able to, is to decide upon the HSC Band that you expect to achieve, and then to aim for the next Band above, as often the difference in Bands is only a few marks.