Contact local universities, technical schools and community colleges. Several schools, including DeVry Institutes, DePaul University and Illinois State University, offer intensive ESL courses. Courses at community and technical colleges are typically cheaper, but select a course that fits your needs.
Find out when the courses begin and take any necessary placement tests before starting.
Go to your ESL course regularly and do the homework. Learning a language takes dedication on the part of the student, and you will not learn English simply by sitting in class. You will need to participate as well as complete all assignments.
Practice speaking English with native speakers. In Illinois, there are a plethora of native speakers, especially at a university, so use it to your advantage. Ask your teacher to pair you with a student who would like to help with English skills or paste an advertisement on a school message board stating that you will trade English skills for skills in your native language. You can also offer to pay someone to help tutor you outside of class.
Take advantage of your location. Chicago is a large city located in Illinois and a cultural bastion. Go see movies, plays and concerts in English as often as possible to boost your comprehension skills.