Can I put html tags anywhere in my posts?
No. You can not use HTML tags in any field except body of the message.
Colons appear in the message dialog box when you try to followup up on a message to indicate that those lines are quoting the previous document.
Your post most likely did not show up, because your browser did not reload the page, it simply pulled it out of cache. Please reload your browser and it should then appear.
What should I post?
You should post any questions or comments about basketball or anything else on the site. Please do not make this a site critique--direct all those comments to email@example.com, where they will be gladly received. And of course, answers to questions posted will definitely be appreciated!