Hello,

I'm a f-1 visa who wants to do freelance in this website : Outsource to Freelancers, IT Companies, Programmers, Web Designers from India, Russia, USA, and more - oDesk (http://www.odesk.com). I already registered, and I already got a client. The site, needs me to fill a W-9 form to transfer the money to me. I do not have a SSN so I can't fill this. The company I will be working for is in sweden. How do I get the ssn?

Apply at SSA. Confirm with your DSO/FSA that this employment is not violative of your F-1 student status.

Apply for ITIN.
Individual Taxpayer Identification Number (ITIN) (http://www.irs.gov/individuals/article/0,,id=96287,00.html)

Hello I am also planning to do my freelancing job while on f1.I had a job and was doing a company,now can I continue that here,If yes my earning will come under which tax?is it 1099Tax?

As an F-1 visa holder I don't think you can be in any employment that gives you paycheck unless it is an on-campus job.

You may be working right from your on-campus dorm, but your employer is in Sweden and you get an hourly wage from them. That is just the same as an off-campus job but telecommuting. Same thing as working from home without a working visa. Unless you get you wage in cash which has no paper trail/record, you'd get in trouble if the IRS audits you and found records of illegal paychecks. As far as I know, you need to use your OPT in order to be engaged in off-campus employment or internships.

Anyway you still need your SSN.

I recommend you consult with someone from the International Students Office at your school.