Being a college student is very different from being a high school student. There are increased academic expectations and a much wider variety of academic, co-curricular and social opportunities at which you can direct your time and energy. You will have more personal responsibility. One of your first opportunities to take responsibility for your college education is register for classes online over the summer.
In May you'll receive an Orientation packet that will include letters of introduction from your faculty and peer advisors and an Orientation and Advising Guide. Read this information carefully - it contains everything you need to know about choosing courses and registration instructions (this info is also online). You have been assigned a specific date and time when the registration system will open for you - this date and time is available in your personalized Orientation and Academic Advising Guide. Your faculty and peer advisors also have access to this information - if you aren't sure when you can register, be sure to ask them!