When you open the page you want to post, scroll down that page until you see "Reply". Be sure you are logged in; if not you'll see the orange "log in" text click on it and you will be automatically logged in. Then cklick inside the long rectangle box with the text: "reply to this post", it will enlarge and above it you'll see a row with symbols for text editing. Now, write your post, paste a link, comment... And that's all to it. Hope it helps.
