Thanks, Anne, for that background on how you found the site.
Re trying to sell a script: Apart from established screenplay competitions like the Nicholl Fellowships in Screenwriting or the Black List website which gives your written material access to over 3,000 industry insiders, the first step is to get representation, and in this GITS post, I detail the path of least resistance on how to do that.
As always, your focus should be — first and foremost — on the writing. I truly believe that if a writer crafts a great script, it will find its way in Hollywood.
Hope that helps!