If you are interested in trying to find a summer internship, there is no shortage of opportunities. The university, college of engineering, CS department, and ACM all hold job fairs designed to help you learn about different companies and find a job. Engineering 100 will have you create a resume as one of your assignments. I strongly encourage you to put some thought and effort into it, as it will prove very useful throughout your time in college (and after you graduate). Also, be sure to actually attend the job fairs. While finding an internship as a freshman can be challenging (although, definitely not impossible; especially if you are entering with some prior experience in programming), the skills and experience you gain talking with recruiters/engineers and solving interview-style problems will help you in the future. I highly recommend going to the first few career fairs just to get a feel of the event (regardless of whether or not you have any experience).

Also, while making a resume, make a GitHub account and a LinkedIn profile, both will come in handy!

Furthermore, the Champaign Urbana Research Park offers both Summer Internships and part time work opportunities during the semester at top companies including Yahoo!, Capital One, Jump Labs, Nvidia and Akuna Capital. In regards to preparing for interviews, some of the best resources include CS 225: Data Structures (often considered a requirement for an interview), the book Cracking the Coding Interview (the most comprehensive book on taking coding interviews), and questions on Glassdoor. People also use sites like leetcode.com, hackerrank.com or the interview prep giving at the Engineering Career Center or by groups like ACM or WCS.