Les - Could be they are talking about method feeders or maybe ordinary groundbait feeder. Let's do the latter first as it is a straight forward rig.
Best way to set this up for stillwater is as a paternoster rig. Can you tie a 4 turn water knot? Assuming you can, tie a mono link onto your mainline that is about 4 inches long after tieing and attatch your feeder to this. Leave the mainline below the link, including your hooklength, between 18 inches and 2 feet long. You may need to adjust this as you go along, but it's a good starting point. Extra tip, always use a snap link to attach feeders as then you have the option to switch between groundbait feeder, maggot feeder or straight bomb.
Method feeders are a bit more complicated, but essentially they are a cage that you mould sticky groundbait around for carp fishing. Your hooklength will then be very short with the bait often pushed into the groundbait mix. The carp attack the ball of groundbait on the cage and pick up the hookbait. The cage is usually heavy and fished inline so that it acts as a bolt rig. See the series of method feeder articles that have appeared on the main site by Pete Webber. These will explain in more detail how they work.
Shout if you have more questions.