It's great that you're interested in writing tales! Definitely explore some of the series to see the world-building and character development we've got—the In His Own Image series in particular is an excellent introduction to the Foundation 'verse. Alternatively (shameless self-promotion on my part here) you can check out the Kiryu Labs Hub for some lighter slice-of-life tales about researchers going to the beach/going camping/going to an anomalous museum. There's all sorts of stories to be told here!
Of course, if you plan to write for the site, remember to make a sandbox page for yourself to keep your works in progress in. When you've got a finished work ready for reading, bring it to the IRC chat and/or the drafts forums for feedback so you can make any necessary edits before a mainsite post.
Astronomy's great. What's your favorite constellation? (I was a big fan of Draco until I started stargazing… too much light pollution where I'm at, can't see much, and I might be in the wrong hemisphere anyway. Orion's always easy to spot when it's in the sky, though.)
If you're nervous about joining the IRC chatroom, you can always lurk in #site17 since it's less busy than #site19. Feel free to message a staff member if you have any questions.
Welcome to the site!