E filing - it returns - employers tan number

hi

i am working in government sector in andhra pradesh

for the FY 2011-12 i was paid income tax Rs.6165/- from my salary through my employer (my total income is 3,46,049/-)

now i wish to file the ITR-1(Sahaj) to e-filing, but in form-16 (get from the employer), there is no TAN Number (Which is need for e-filing). i am asking all of my collegues for employer TAN number they says that "WE DONT KNOW"

can any one please help me to get the employer TAN number 

or to file the e-return through online