Most winch manufacturers make a generic plate that their winches bolt onto. You are then responsible for figuring out how to make the plate mount to your vehicle.
There are several ways to do this...
1. Purchase a bumper that is built to house a winch
2. Modify your own bumper to hold the plate (involves welding and fabrication)
3. Make a bumper
Of the three options, I prefer #3 myself. Making bumpers isn't all that difficult and they are great entry-level fabrication projects. You can go from mild to wild, limited only by your skill and patience.
Some of the ones we've made at my home shop rival anything purchased. We generally start out with tube stock of a size appropriate for the project, then modify that to fit. The latest couple of bumpers were made from welded plate. We made a 1/8" luan (thin plywood) bumper first by cutting and taping together all the necessary pieces to shape the bumper the way you want, then transfer each piece to steel (3/16" or 1/4") and cut each out. Weld the pieces together, grind smooth, and paint -- brand new custom bumper.
On my current Ranger project, the winch will reside where the factory radiator sits (the radiator is being relocated to the rear of the cab) and I'll build a custom crossmember and bumper to house the winch so that it can both winch the truck and also cinch up the front suspension for steep climbs. I'll post pics when I get that far -- right now I'm still modifying the frame rails and making spring hangers. links, etc., for the suspension.