I'm a new SO user. Researching about a particular feature of the Android Market, I have found exactly the right question I wanted to ask. It has an accepted answer, and I know it's clearly wrong. AFAIK,I've should commented below the accepted answer, but cannot because of my low privileges. I opted to point the error in a separate answer. Did I proceed well?
No. Answers are not for posting comments. If you link to the answer you posted, I can convert it to a comment for you.
New users are not allowed to post comments, because the primary purpose of the Stack Exchange network is to serve as a question and answer platform, not as a device for extended conversation.
New users are required to achieve 50 reputation to earn the privilege of posting comments anywhere. Anyone who can achieve that probably understands the SE platform well enough to use comments responsibly.
If you have a better answer, please post it as an answer! Stack Exchange allows, and even encourages, providing new answers to old questions when the existing answers are wrong or obsolete.
If you know that an existing answer is wrong, the proper behavior is indeed to comment and downvote, but this possibility is not offered to new users. While this is unfortunate in a case like this, it steers new users away from comments, which is usually a good thing as Stack Exchange is all about questions and answers. Please stick around; as you participate in the site, you will gain reputation points which unlock features beyond being able to post questions and answers. It takes 50 reputation points (that's 5 upvotes on answers) to be able to comment.