Here on the astronomy for beginners blog, should you as a reader, wish to respond to one of the articles then you can do so by leaving a comment on that post. Just click where it says "0 comments" or "3 comments" or whatever, and start writing. But if you wanted to write an article yourself then you'd have to start up your own blog. How many blogs do we need about astronomy for beginners?
Additionally, if you spotted a mistake in my writing, or an incorrect fact, there's not a lot you can do about it. You could point it out by leaving a comment as above, or you could email me, but it may well be something reasonably trivial and you decide it's simply not worth the bother. The moment passes.
So I've started up an Astronomy for beginners wiki over at wikispaces. This is not meant to replace or detract from the blog, it's just a complementary addition.
On the wiki you can just click the "edit page" button and change the text right there and then. You can also create new articles of your own, and link pages together using wikitext links. That's enough about it for now. If you have any queries you know how to ask.