You have to be accepted into a school's nursing program. Registration for the nursing classes is only open to students who have been accepted. If you are interested in going to nursing school you should research different nursing programs in your area and find what suits you best. Then, find out the steps to apply there such as entrance exams, pre-reqs, etc.
Many credits do not transfer. However, in my state (North Carolina) the community colleges are associated with my state's universtites (the University of North Carolina colleges). Your credits are guaranteed to transfer. For example, when I finish my ADN program at my community college, all my credits would transfer to a BSN program within the University of North Carolina systems that offer a BSN.