If you want to become IAS then first of all you need to complete your graduation in any discipline from a recognized university, and you can also apply in final year, you need to be 21 years old as well, 11th is too early to start the preparation, right now your focus should be on studies and thinking more about what discipline you want to pursue your graduation, if you choose humanities then it'll become comparatively easier to deal with as you'll anyway covering the core part of UPSC syllabus, some of the things which you can do initiate the preparation is firstly be acquainted with the syllabus, go through it and previous year paper to understand what are the demands of exam, what all areas are to cover while studying, start off with NCERTs and the move towards other standard books and keep resources limited, revision is the key here, this is something you can do in gradual manner from college itself, but it isn't recommended at all that you go through these steps right now as you're in 11th, so focus on studies and doing well in it.
To become an IAS officer, After 10th you should join any group classes in class 11th.
After intermediate, complete your bachelor degree with any subject of your choice from a recognised university or institution.
After graduation, take coaching class for preparation of UPSC exam... Then write the exam i.e prelims and mains....
If you qualified in mains, then you will called for an interview in Delhi.
If you bring rank between 1-95, then you will become IAS officer in India.
Hope this information will help you