Hi there! Always nice to have a long-time reader join.
Anyway, now that you're a member of the site, you can:
- vote on articles
- comment in discussion threads
- create your own forum threads
- edit site pages (if you didn't write it, please only make spelling/punctuation/grammar fixes, or ask a staff member if you're unsure)
- contribute to collaboration logs (things tagged with "collaboration", which are subject to review by staff and the author)
- write your own stuff!
Of course, what you do on the site is totally up to you; it's best to take your experience at your own pace. There aren't any requirements for site activity. :)
What programming languages do you know? Also, have you taken a look at the SCP Wiki Usertools?
If you haven't yet, maybe drop by the IRC chatroom and introduce you to other Foundation personnel. There's usually a few people around talking about all sorts of things.
I hope you enjoy your time here. Welcome to the site!