i m last year engg student with electronics specialization and now i hav applied for UPSC engineering services exam how should i start n also suggest me classes for it .

You need to apply for it when the notification comes around mid of Feb 2011 and then prepare yourself for the prelims which would be held in June 2011. But I think you must target UPSC exam of 2012 and not of 2011. Get some study material from a coaching institute. Rau's coaching institute and T.I.