Still don't know how to comment? Here's how.
At the bottom of each post you'll see a "Login with your username and password below. New User? Here's what to do." Since you're obviously a new user, click that link and follow the instructions below to choose a username, a password and an optional email address.
Once your comment is approved, it'll show up and you can come back and keep refreshing to see if someone else has responded to your comment. How very vain of you.
If you're still having problems, check out the commenting FAQ.