If you want to start a new rp, it’s best to put up a post with a poll on the New Ideas Thread first to get an idea of who would be interested before posting your sign up thread
There’s a bunch of helpful threads in the ‘Announcements & Tips’ subsection for getting started in rping so I’d recommend checking it out
An SG is a story game - those are more controlled by the person writing them but occasionally the owners of the characters will be given choices for how their character will react or where they would go