Heyo!
I see you've got a sandbox and a forum thread, so you look like you've got a solid start. Remember to consult the resources available in the Guide Hub as necessary, and ask questions when you have them!
So far as lore goes, the best way to get a feel for it is to read, both articles and the discussion pages where the audience reacts. The site's standards have changed pretty notably in the past several years!
If you're looking for SCPs that are a good example of current 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 six 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.
Anyway, best of luck!