LZ,just google “Algorithm Complexity” and the second result is what you want. http://en.wikipedia.org/wiki/Analysis_of_algorithms
Please make better use of Google and Wikipedia, as they can really help you a lot.
The fact that you ask naive questions does not matter. What truely matters is your attitude toward problems and the way you solve them.
BTW, what you ask should belong to Courses of Data structure and Algorithm Analysis. It's understandable that you do not understand since these are typical CS courses. However, this should not be your excuse, as you are currently applying for CS study. People including those College Profs would expect and presume you at least have these basic knowledge. In addition, EE people are familiar with Matlab and Algorithm Complexity is not sth we doesn't consider at all.