What Causes A Scab On The Shin?

I am 71 years old,6'3", and weigh 195 lbs. I have had a scab on my shin for about two weeks after a board scraped my shin. The scab started to ooze a little blood after a minor bump. I applied polysporin under a bandaid overnight. When removing the bandaid, the scab came off too and I now have an open wound about the diameter of a quarter. The skin around the ankle is reddish and feel hot. How should I treat the wound? Hydrogen peroxide? Polysporin? Leave open? I am in generally good health.