If you wish to quote one or more posts in your reply you will find the Quote tools in the lower right corner of each post.
The text-link Quote will open the post page with an inserted quote in body of the message
The button, if pressed, will highlight, meaning that the post will be quoted when you press the reply button. You can select several posts for multi-quoting. All the selected posts will be shown as quotes in the body of the message when replying.