Just visit the link and sign up for the online exam. All you need is to register for the practice test and have a pdf copy of NISPOM available and you are ready to go.
The practice exam has 110 multiple choice NISPOM questions and is timed for 120 minutes. You can take it up to 20 times in a six month period as you study for the actual exam day. Each time you test, the questions and answers will appear in random order. Give it a try.
For practice purposes, download the electronic version of the NISPOM and use it to help search the answers to the provided test questions. Use a timer to count down 120 minutes for each practice exam.
Register for the exam here: https://www.classmarker.com/online-test/start/?quiz=jdm5dbdb6cb9c613
You can find additional certification training and resources at http://www.redbikepublishing.com/ispcertification/