Communication on arrear demand

Hi all,

I am newbie and I have taken to efliing of income tax returns for the past three years.

Yesterday I got a demand notice from IT department with the following details

Can someone explain to me what section 143(1) means  even i am salaried class , n all tax paid by my employer through TDS , i have F-16 ,paid tax statement from employer and even acknowkedgement also for File the returns

STATEMENT OF ARREAR DEMAND
AY : 2008
SL.NO : 1
SECTION : 143(1)
DIN : 20 digit number
AO (Intimating Demand) : ITO WART 46(4)
DEMAND AMOUNT : 69K
INTEREST U/S 220(2) INTEREST CALCULATED TILL : 0

Can someone explain to me what section 143(1) means  even i am salaried class , n all tax paid by my employer through TDS , i have F-16 ,paid tax statement from employer and even acknowkedgement also for File the returns

Also How can I contact the Assessing office .and sombody guide me to correct this error from IT dept

Thanks for your help.

THanks