You are mixing terms. You register your screenplay with the copyright office and/or the Writers Guild of America to protect yourself. You do this before you hand the screenplay around to others in case some thief tries to steal it and claim your work as their own. You must pay to have it registered. You don't have to register if you don't want to.

Selling your screenplay is another issue all together. You can try submitting it to contests (costs you money but if it wins you make money and get attention and possibly feedback). You can try sending letters to Agents and managers and producers hoping to entice them into requesting you send the manuscript. If they ask you to send it and they like it they may buy it.

There are also websites out there that you can post your screenplay on where you might get feedback and perhaps if you are lucky an agent/manager/producer might notice you there.

It is all a crapshoot if you don't have connections in the industry but they say a really good screenplay will get noticed.

RJSchwarz

I think the contest route is one of the best avenues for anyone without connections. If you can find a reputable contest, and your work is good, it will get noticed.

As a former reader, I can tell you that 99.9% of everything submitted to me needed a ton of work. So regardless of where you submit, make sure your work is 100% good! That means a great story as well as great presentation.

Go here: www.filmmakingstuff.com