Hi, Craig,
When you reply, click the "Use rich formatting " link and wait for your browser to refresh the page.
In the new reply page, you should see a Quote link, which will default the text of the post you were on when you clicked Reply into the body of your reply, with the HTML quote tags.
That's how to quote a single post. I don't know if FSM's software offers the functionality to quote more than one response at a time. Other forums I belong to have that feature; it allows you to quote multiple posts all at the same level in your reply. Of course, you can use cutting and pasting as a workaround to quote multiple posts in your reply.
Hope that helps!
Brad