Hardwood floor maintanence, cleaning, repair...etc? Please help?

I just bought a house an it is real hardwood floor throughout. I have done a lot of searching and I am still confused. I believe it is a finished polyeurthran hardwood floor made by Bruce (i found some left overs in the box still). When I mop using Clorox readymop, it doesnt take away the footprints and it looks dull. I have also tried Murphys Oil soap and it is the same. What does refinish mean? There are some cracks too so how do I repair that? How often should I mop? Is a steam mop a good idea? Please help