I just stumbled onto this Superstar business. So, I guess since we're at round 2 or 3, it's a little late to enter? Or if not, where are the new contests announced?
You're too late. The open call was round 1, and entries for it had to be submitted by November 14.
There has been rumours floating around that there might be another contest sometimes next year...
Look at the 'writing exercise' thread here. Others are posting their 'entries' there for critique and just for kicks. I imagine that there will be a thread for each round's wannabes.