If you enjoy writing stories more than scientific tone articles, consider creating a tale! We've got a lot of worldbuilding and character development that happens outside the mainlist; the In His Own Image series in particular is an excellent introduction to the Foundation 'verse.
To get started with writing, you should create a sandbox page to keep your in-progress works, references, or ideas in development at. When you've got a draft ready to be read, bring it to the IRC chat and/or the drafts forums for reviews so you can make the necessary edits before a mainsite post.
You can also get your concepts polished up in the Ideas and Brainstorming forum before you commit to writing up the full draft—it makes the writing process go a lot smoother when you start off with a solid idea the audience likes!