Depends on your tractor Kenny and what options are avilable already on it.. Of course, this is assuming you already have a fel on your tractor. All you are adding is power to open and close the grapple.
1. IF your fel control valve has the adaptability to add another spool valve to it, you just do that and run hyd hoses down to the grapple cylinder(s). Return utilizes the loader valve's return circuit.
2. IF your tractor already has rear hyd valve(s), you can utilize that, but it means you have tied up that valve with a grapple and can't use any rear 3 pt hydraulically powered/activated implement unless you add another stack on valve and control back there.
3.Most tractors have what is known as a "power beyond" circuit built in from factory. It means exactly that, hyd power beyond that which came with the tractor. You will have to find the PB port, remove the plug, and tie your hyd hose into that threaded port. Sometimes that port is on the transmission housing--sometimes it is on the control valve for the fel. You will need to mount a control lever somewhere (usually on the fender) and will have to plumb in a return line, usually back to the fill hole by use of a tee. When in the center position, hyd power runs thru the center of the grapple lever valve and back to return without affecting your fel or your rear hyd ports.
4. Another option, is to tee into the line that supplies hyd pressure to your fel, add a control lever to the fender, and plumb it in such a way, that hyd power runs to the grapple lever valve, out that control's return, and then on to the fel control valve and in some cases you may have to run a return line back to the hyd oil fill port. This allows full use of the fel and any implement ports on the rear, as well as the grapple. You just have to fit a tee into the oil fill hole so you can both get return and still pull a plug from the top of the tee to add fluid. This is how we generally added a grapple to a mid size Kubota. The only down side to this option, is since the hyd pressure is pulled from the fel circuit, you may see reduced pressure at the fel lift and tilt, but most people don't worry about it since once the grapple cylinder(s) close or open they then operate the fel valves. Otherwise would require 2 hand operation, one hand operating the up down of the fel, the other hand operating the grapple. I've never seen a need to do that. You are either opening/closing the grapple or raising/tilting the fel--not all at the same time. Once the grapple lever is released, it is spring loaded to neutral, and this locks the grapple in whatever position you had it in.
Some people just opt for the upper part of the grapple, mount it to the existing fel bucket and use the grapple in concert with thw bucket instead of taking the bucket off. In those cases, I've seen people add teeth to the bottom leading edge of the bucket for the grapple to have something to press the load into. Most people tho, just put QD connections on the grapple lines, remove the bucket and install the grapple. Remember to use QD connections near the point where the lines go down the fel arms so you can drop the whole fel off if you need to.
Not a very clear description I'm sure, but it is much easier than it sounds.