Plenty of fish and OK Cupid are both free. POF does have a version you have to pay for, but the free one has all you ever need. The only difference is with the paid version your picture shows up more often and ahead of other people. It's not worth the money though if you intend on spending an adequate amount of time on the site to find a date yourself.
Just create a good profile, have decent pics that are recent, and put effort into it. Also don't feel like it will happen over night, it can take months to find someone you really click with. But stick to it and you will find someone.