Ibad,
As far as the holds on your account, one is the requirements to attend a registration program and that will not be taken off until you participate in the program in August. Also, international students on F-1 student visas will need to check in with International Student and Scholar Services (ISSS) before being able to register for classes. Information on the check in process can be found here: http://www.ips.uiuc.edu/isss/ Another student asked a similar question about registering for classes recently, and below is my response to that student:
You will be able to register for fall classes during your registration in August. Remember that when freshman are registering for classes all upperclassmen (sophomores, juniors, and seniors) have already registered, so it is true that some classes and times may not have open seats. Thus you will register for classes where there is space available. You will be able to get the classes you need for a particular semester to stay on track for graduation, but you will likely not be able to get all the classes or times that you want. For example, it is probably not a realistic expectation to have no classes before 10 a.m. and/or no classes on Friday. If you are not able to get into all of your first choice classes as a first semester freshman there will be opportunites to get into those classes as an upper level student.
Your advisor for summer registration will work with you to make sure you are taking a good schedule in your first semester. Further questions about registering for classes can be directed to your advisor when you arrive for your summer registration day.