Adrain,
There is no problem as long as you practice first. Once you have picked your rings you need to buy some whipping thread; the best is Talbot Nylon from all good tackle shops. Next you need some two pack seymo whipping sealer and epoxy (it comes in a three bottle pack for a fiver). Now the best bet is to get somebody to show you how to whip on the ring, if you buy all the stuff from one place I am sure they will show you. Next practice dry whipping a mid sized ring on the rod between two existing rings. Make sure the end of the ring is flush with blank the and not sharp, a little filing and sanding of the ring foot may be required. Use a slither of tape to hold the ring removing this as you get the whipping close to it. When you have done at least three good whips, removing the ring each time then its time to start. If not, you can take the kit to a local tackle shop who will finish the job off. Now measure where the rings fall and write it down. if you are carefull you should be able to remove the existing rings without too much difficulty. Lightly sand the blank where the old rings where then whip on the new. Use the sealer, dry, then the epoxy. Only use quality rings, why noy buy one ring and a spool of Talbot then give it a try!! Go on you will suprise yourself, next step builing a whole rod!!!