The best way to find jobs working online is by searching via Google or another search engine, then when you find an opportunity, search the opportunity to see what has been posted about it. By doing this you can eliminate getting caught up in a scam and find some legitimate work online.
The two most established freelance sites are Odesk and Elance. Your biggest obstacle is likely to be your command of English: to be really successful in freelance writing you need a very high standard of English grammar and spelling. I think English is your second language so that will be a major challenge for you.