Hi yourself.
If you are interested in posting a story about one of your families, the misc. story category would be best. If you want to post a story of one of our projects, such as the asylum one, project stories is where it should go. A great tip would be to always start your thread with a post about what your story is going to be about, and it it's a project story - please link to the project so people know what rules you follow.
2-3 times a week seems pretty normal. It is also common for people to update a lot for a couple of days and then not at all for a while. It really depends on how often you play. There are no rules about how often you have to update your story.
If you are just starting out I would suggest following a project and just cataloging what your sims are up to, I'm sure they will give you all the inspiration you need.