Matriculation happens when the admissions office has accepted your application to begin work toward a particular degree. Registration is the process of officially enrolling in courses. The college catalog serves as a contract between you and the university. Your declared major will determine the number of required credits you must take. Course number will indicate the level of the course offered.
Academic advisors can be very helpful.
12 semester credit hours is considered full-time. Avoid time conflicts when scheduling courses. Some courses require pre-requisites. Each credit hour is a unit of measurement. Imputed courses are taken with no credit applied toward graduation.