So you're talking about two things, one being quotes, the other being signatures. When you press the little +Quote button, it adds whatever comment you pressed it under into your little multi quote queue. When you have quotes loaded up, you should see where it says "insert quotes" underneath the comment window, and when you do that it drops all of the quoted posts into your comment, it's useful if you're trying to reply to multiple people.
To add a signature, simply click the thumbnail to your profile and go to the "signature" setting, you can edit your signature from there.
