The Office of International Student and Scholar Services has a Transportation webpage with useful information about getting to Champaign-Urbana. The most common way students arrive is by flying into Chicago O’Hare International Airport (ORD) which is roughly two and a half hours from Champaign-Urbana. There are several shuttles that run between the major Chicago airports and campus and an Amtrak train that runs from Chicago Union Station to Champaign. There is also a small airport in Urbana-Champaign called Willard Airport that you can fly directly into.
Before you arrive to campus, it would be a good idea to familiarize yourself with campus. You can also see where your housing will be located if you are using university housing. Follow the link provided to view the campus map.
http://illinois.edu/files/map.pdf (printable version)