If you want to quote multiple posts, then at the bottom right of every post, next to the "Quote" button, you will see a button with a quotation mark and a plus sign on it. On one of the posts that you want to quote, click that button, and it will become a gold color. Repeat this for the other posts that you want to quote, and then click the "Post Reply" button.
If you want to split up a single post into seperate quote boxes, so that you can comment on specific parts of that post seperately, then you will need to add the vB code quote tags into your post text yourself.
Regards,
Retro.