how do i get a social security number

Hi all

I moved here in November, and have got an NIE number so went out looking for work. I have been offered a job with someone but they said i need to bring in my NIE number and Social sercurity number so they can give me a contract.
I said i had an NIE number but not a Social Security number i asked them how i went about getting one but they did not no.

Since then i have asked around and everyone so far has said that when they apply for a contract their accountant gets me a social security number at the same time is this correct or do i need to get a solicitor to get one for me. before i get a contract from work.