The process you follow to register depends on your student status either nonmatriculated (NM) or graduate nonmatriculated (GNM) and the academic quarter. See descriptions and links to register below.
GRADUATE NONMATRICULATED (GNM)
You should register as a nonmatriculated student (NM) unless you are planning to apply the credits you earn toward a specific graduate-level (master's or Ph.D.) degree. Most people will fall into this category.
You should register as a graduate nonmatriculated student if you plan to apply the credits you earn toward a specific graduate degree in the future. "Graduate Nonmatriculated (GNM)" status does not refer to any degrees you currently hold, but to whether or not you plan to apply the credits to a masters degree or Ph.D.