Download these to your computer and then transfer them via USB to your Kindle.
All of Edwards works are available online, as well, at the Yale website.
If you are new to Edwards I would recommend two works to start: The Religious Affections, which is an essay on the signs which accompany a true saving experience (a work of God in the heart). And Charity and Its Fruits, which is a series of sermons on love from 1 Corinthians 13.
Download from here.