freelancer.com----scam or legit?

i found this site and signed up on it. i opted to give it a try, but i wind up confused. so i bid for some projects that i'm willing to take. then what? again my anxiety attacks on sending out my articles as sacrificial lambs to get a job done. i'm never sure if it'll suit their pitch. what should i enclose on my profile for them employers to consider me on their wing? please someone, illuminate me. ~.~