I'm thinking alternator
 

Hi guys
my sportsman started with jumper cables,then I let it run for quite awhile.i noticed my instrument lights were going bright and then dim.my headlights wouldn't work,neither will my winch.
would it be the battery or alternator.
any ideas will be greatly appreciated

See what the voltage is at the battery while it's running at an idle or a little above. Should be around 14 volts or so. If it's not charging usually a regulator is the problem. Don't over look the battery itself. Have it load tested. If the regulator is charging ok,but if the battery has a dead cell,it can't hold a charge and would need to be replaced. Check the wires leading to the regulator. Depending on model some have had a habit of wires coming disconnected. May be as simple as that. You can do a general stator test to make sure it's ok. All yellow wires leading to the regulator from the stator should have some small resistance between each other and no yellow should short to ground.If needed, regulators are cheap on ebay or amazon.