Accepted, now what?

I was accepted to the policy track, looking to switch to infosec. I was thinking of taking pub6725 to start( 20 years since I last was in school). Whi do I talk to work with advisor? Just sign up? Do I need a course plan? Feel like I'm missing some info thread. I literally got accepted for fall 25, what are my timeliness just for this semester at least and what or who do I talk to?