There are a few special forms you can use in your response text that get automatically translated into active links by the system. Anything that looks like a web URL or a mail address gets activated:
The [Hotlist] page has a special feature not found in any other ACME News page - it automatically reloads itself after ten minutes. The idea is, you can leave a browser window sitting on that page all day, and whenever someone posts new responses you'll see the indication pop up within ten minutes. Pretty cool.
If you want to quote someone's text when you respond, just click on the response-number link in the response header. You'll get to a page with just that one response, and in the posting form you'll find the text of the response already inserted, with '>' added at the beginning of each line, too. Remember to edit out any parts of the response that you don't need to quote - other people don't want to read the whole thing again. Just quote the relevant parts.