There are new items under each post in this blog: "Add a comment" and "Trackbacks", from Haloscan. They provide you with a more friendly interface to leave comments and to manage trackbacks: Haloscan does both and is free.
Blogger (and Blogspot) not implementing trackbacks is annoying and difficult to understand. Instead, Blogger offers backlinks, which do not offer the same features. Emily Robbins nicely explains this in her post HaloScan brings TrackBack functionality to Blogger. She also explains how to send trackback pings with a "Haloscan-enabled" Blogger account.
See links to your right - I have added two links under "Blogging Stuff": what are trackbacks and what are backlinks. Take a look at both, and at Emily's article, above: it'll become clearer.