You can use the [link|http://z.iwethey.org/forums/render/content/show?contentid=57396|WeeCodes] to easily quote text (and do other HTML goodness, if you check the "Process WeeCodes" item on the New Comment screen), or you can use the "Quote" button down below (though it's a little tricky to get used to).
The "[quote]Text I'm quoting[/quote]" set (withoug the quotation marks) is your friend and a good feature to get to know. It results in:
Text I'm quoting
Ask if you have questions, and experiment in the Test Forum if you're unsure.
HTH.
Cheers,
Scott.