This question can't be answered short and simple. There are so many aspsects to successfully trapping any furbearer. If you intend to start fox trapping with the goal of continuing for many years, I'd recommend getting some books, videos, and try getting with someone who is willing to SHOW you what to do. Buying the right size trap is just the beginning. The prep procedures that must follow the purchasing takes time and money. You just don't buy traps, set them, and catch foxes.
If you just want to catch the ones you've seen at an active den I'd recommend snares instead of traps. Snares are cheap, quick to get ready, and very effective. Mating seaso for foxes is mere weeks away, and watching the dens from a distance might enable you to bushwack them. Calling SHOULD work too. Good luck.
