The calculator below should be self-explanatory, but just in case it's not: your chi-square score
goes in the chi-square score box, you stick your degrees of freedom in the DF
box (df = (NColumns-1)*(NRows-1) for
chi-square test for independence), select your significance level, then press the
Enter your values above, then press "Calculate".
This site features a number of different chi-square calculators which you might find helpful.