Heyo.
If you're interested in writing for the site, make sure to create a sandbox page for yourself, and get any drafts you write up there shown to the IRC chat and/or the drafts forums for feedback prior to a mainsite post.
The chat is also a great place to hang out at and meet fellow Foundation personnel. You can get a feel for the real-time critique given there, and also toss around ideas with others. Also, if you'd like to ask about your ideas before you write them up as drafts, you can make a thread in the Ideas and Brainstorming forum to see what people think of the idea and whether something similar has been done before.
Also, since you're coming from the game, you should familiarize yourself with site standards. I recommend reading the high-rated Series II and III articles (SCPs with numbers from 1000 to 2999). There are many inspirational articles in Series I, but articles written four or more years ago are less likely to be up to current community expectations, even if they've got a lot of upvotes. Remember to pay attention to how old an article is when deciding if you'll use it as a guide or not! You can (and should!) check article age by clicking the "History" link at the bottom of a page, and looking for the page creation date.
Furthermore, if you've got any questions, comments, or concerns, feel free to PM me or another staff member.
Welcome to the site!