You have two options to get it signed, either you can ask the CFI of your school to sign it or you can get it signed by an gazette officer in India (any government employee). Since you haven't yet sat for your exams, I suggest you ignore the Application for Issue/Convervsion of Pilot License as it holds no good for you at the moment.
Also, please be careful while filling up the Pilot Number form you wouldn't want to make any mistakes and not have your computer number for the next attempt. Get your 10th and 12th marksheets attested by a gazette officer and also your CPL, if you dont have a CPL then your temporary CPL should do, also send the first 25 hours of your log book! Get them attested too. Hope this helps you, good luck