Have to totally disagree with you khargonkar, "The aviation (enginering ) field is for the approved and licensed person only" is complete rubbish.
I've worked in Technical Services for many years, and many tech services engineers have varied qualifications.
The most common TSE's will have either done an Aviation or Mech Engineering degree or will be licensed guys/gals who have spent a few years on line/base maintenance before moving to TS.
I would advise you to check airlines/MRO's that are close to you to see if there are any vacancies available.
As for the job description, you could end up in different departments depending on the struture of the Eng dept, ie Systems, Avionics, Structures, Powerplant. Again depending on the Structure you could be involved in some of the day to day issues that arise with the aircraft or more long term things like evaluation of Airworthiness Directives, Service Bulletins, Reliability, Maintenance Schedules etc.
Typical career path could be something like tech services eng, senior tse, tse manager, engineering manager........etc.
Hope this was of some help.....