A wrench light has come on in my 2006 Honda Accord: what does it mean?

I JUST HAD AN OIL CHANGE DONE A COUPLE WEEKS AGO AT WAL MART. THEY CHANGED MY OIL AND CHECKED ALL MY FLUIDS, THEY SAID. SO DO I GO AND CHECK AND SEE IF THEY REALLY DID IT. PLEASE TELL ME WHAT TO DO. I AM 64 AND DON,T KNOW MUCH ABOUT CARS.

just needs to be 'reset'.