How do I invite a friend to my project?
If your project is private, there are lots of ways to invite your friends.
On your project home page, you'll see an "invite URL". Copy that link and send it to your friend however you want--in an email, IM, or anything. When s/he clicks that link and creates and account, s/he will automatically become a member of the project.
You can also directly invite your friends by email or Facebook. Click the "invite" link from a project page.
If you have contacts, you can invite them all with a single click from the project invite page.
If your project is public, you can simply send your friends the link to your screenplay.