You can reply to posts and post statements/opinions in other threads, you just can't make any new threads until you've reached 20 posts or have
offered a good enough sacrifice to the godlings that run the intrawebz.
There you can learn how to do things like properly quote articles and give the correct link to the source. You will learn how to post pictures. You
can learn about formatting. Or embedding videos. All that activity "counts" plus you learn how to make your threads all purrty and stuff!