best thing to clean the wound with is Nolvasan (chlorhexidine diacetate). This is what the vets use to clean animal wounds, and I use it to clean my enclosures as well (much safer than bleach!). Put the snake on newspaper or a towel (remove anything it could get caught in the sore, and clean it daily.

Unless you can get a special type of antibacterial from the vet (I forget the name, I have a small container of it at home though so I can check for you later but the salve I have was for an abscess in the snakes mouth) you can use neosporin instead but the problem with anything type of salve on the exterior snakes is that their skin/scales are not very absorbent so mostly they will just run it off the exterior.