This introductory article by Rabbi Mendy Hecht explains the commandment of ‘Hafrashat Challah’ (‘separating challah’), complete with the English transliteration and
This article from Chabad.org provides biblical, Talmudic and halachic reasons for the custom of covering the challah before and during the HaMotzi blessing. In
This article from Chabad.org discusses the halachic (legal) and Kabbalistic (mystical) explanations for ‘scratching’ the Challah before the blessing over the bread on