Complex sentence: Prior to his visits at Auschwitz, Pressac, a French national, was instructed by Faurisson how to go about conducting his onsite examinations in Oświęcim; and warned against the tendency to see "falsehoods" everywhere.
Split into simpler sentences: Prior to his visits at Auschwitz, Pressac, a French national, was instructed by Faurisson on how to go about conducting his onsite examinations in Oświęcim. He was warned against the tendency to see "falsehoods" everywhere.