You didn't do anything wrong. Go back to the post you mentioned where you actually posted. You'll see an edit button, click on it. Then scroll down to go advanced button and click on it. Then scroll down to where it says thread subscription notification type and from the drop down menu click on no email notification and then just below that click on the save changes button.
As far as the pins I couldn't tell you other than to go to Rules and FAQ click on that and scroll all the way down and click and read.