everything you need to prepare for the NATA exam is available here on DQ Edge itself. Like for which topics to study and prepare, you can go to the LEARN section, there you will get to know the syllabus for the NATA exam. Start your preparation from here and clear your concepts. You will be able to keep the track of your performance - which topics you have covered, which needs to be covered. From the graph given you can schedule your preparation.

If you want to know what strategy you have to follow during the preparation, then you can go to the Article section of the DQ Edge. There you can go the through various articles on strategy, syllabus which will help you in your preparation.

Now coming to your question that you are from hindi medium school and not comfortable with english. See the thing is sooner or later you have to learn english. It will be hard for you in the beginning but you can overcome this problem and will take time to show you the results. If you feel its hard for you then its better to take english classes for the same. I hope this helps with your preparation, if you still have doubts you can ask.