Once approved for testing you can take the written and practical exam at the next meet (depending on availability). The written test covers material in the USA Powerlifting Technical Rule Book which can be found here: http://www.usapowerlifting.com/wp-content/uploads/2014/01/USAPL-Rulebook-2015.NGB_.pdfYou should read the rulebook completely before taking the test. Written test is open book.
Becoming a referee is a great way to give back to the sport and gain a wealth of knowledge. With the growth we have had in our sport we have run short on people who can help. Your participation is much appreciated.