The "Quote" command works like this: [*quote] Yadda yadda yadda [/*quote]
In the above, please ignore the asterisk (it is only there to keep the command from activating). Without the asterisk, what you get is this:
When you click on the "Quote" button on the text box (or use the "Quote" function in the Reply), it automatically puts a quote/endquote at the beginning and the end. If you want to answer parts seperately, all you have to do is put an endquote ([/*quote], again, ignore the asterisk) at the end of the portion you wish to seperate. Anything within a quote/endquote will go in it's own text box.
Don't forget that you will have an endquote at the end of the post that you need to either erase or use. You won't be able to post until you get a matching number of quotes/endquotes. Incidentally, the other commands work similarly.