A few resources for BIML.
Varigence site – https://www.varigence.com/
Varigence has a few tutorials on their site to get started. https://www.varigence.com/Biml. Varigence also hosts a forum for developers available via https://www.varigence.com/Forums?forumName=Biml.
Cathrine Wilhelmsen – https://www.cathrinewilhelmsen.net/
Cathrine is a consultant, technical architect and developer, focusing on Data Warehouse and Business Intelligence projects. She has a wealth of information on her blog, with a number of BIML primers along with code.