2005 Chevy Cobalt Spark Splugs Engine Check

I have a cobalt LS 2005 Sedan and would like 2 change spark plugs, wouldl like to know exactly were they r located, I have done some research but not sure, also my engine check ligth comes on but what I do is take the terminal out of the battery and then stays off 4 about 2 or 3 weeks and then back on, the car runs fine anyway with no problems. I know it could be just a sensor problems. Give some advice about the subject. Thank you.