Well, you should know that most of the people that use this forum are older (16-20 range) and there are a lot of.. expectations, when it comes to posting. I could probably write an essay on posting etiquette (maybe I will some day), but suffice to say if people don't post well they become very unpopular very quick.
Yes, that is the bare minimum. We've had 13 year olds that haven't been a problem and 16 year olds that are completely insufferable. The most important things to learn are:
1) When to post (or, when not to post)
2) How to post without looking like a fool
As far as 1 goes the idea is to only post if you have something meaningful to contribute; this goes doubly for making new topics as that is a far more serious action.
For 2, Don't post in an old topic (one in which the last topic is more than a few months old) unless you have a REALLY good reason to, and making a new thread for a topic that already exists is worse. As well don't use special fonts/colours/text sizes unnecessarily and don't use too many emoticons (this is in the actual rules). Oh also roleplaying is discouraged, as is posting for the sake of increasing one's post count.
The commonly given advice is to "lurk" a forum before posting in it, meaning you should read old topics and posts by people before you to get an understanding of what is acceptable and what isn't, as well as what has been discussed to death and what hasn't. If you can manage all these things then you would do fine in this or any other online message board community.