For this achievements, you have to complete the quest "A Book for Firebead".
Head to Feldepost's Inn in Beregost, and buy the book "History of the Fateful Coin". Then head to Firebead's Home (Right accoss the street from Feldepost's) and talk to him to finish the quest. You do not need to talk to him before buying the book.
More details about the quest:
http://baldursgate.wikia.com/wiki/A_Book_for_Firebead