Method 1
Find the post you want to quote. Copy the text you want. Hit “Post a reply.”
From the formatting boxes directly above the text box, hit “Quote” and paste the text right where the cursor is. It should look like this, except with square brackets where I’ve used regular brackets:
{quote} selected text {/quote}
Place your cursor after the whole thing, and start typing your response.
If you want to respond to several parts of a post, you can use
Method 2:
Find the post you want. In the upper right corner, hit the “quote” button. The entire post will be reproduced, with {quote=”username”} in front of it and {/quote} after it. (Again, there will be square brackets everywhere I've used regular brackets)
For each portion that you want to quote, you need to put {quote} in front of it and {/quote} after it. Just type in as many of each as you need. Type your response to each section and DELETE the remainder of the text.
Now you’re set to type your devastating reply! Be brilliant!

