Answer:
Rabbits are very territorial. They use the same corner to potty in every time. You should first observe which corner this is. THEN put a litter box with either dirt or clay litter in it in that corner. (using fancy litters with chlorophyll crystals etc. may encourage the rabbit to eat the litter!! Not a good thing.) After your rabbit starts using that litter box you can leave his cage door open and he will return to the cage to potty. Eventually, if that is your goal, the cage can be removed and the box left in that spot and they will return to the box to potty.
Well, to start off all rabbits are different. Some rabbits will learn it quickly others never will. Mine did. All you need to do is buy a litter pan (sometimes it comes with the cage), then put newspaper/bedding in it and then when your rabbit poops/pees pick that bedding up and put it in the litter pan. Or if your rabbit already poops/pees in one corner put your litter pan there. hope i helped :)
You determine which corner of the cage your rabbit uses for a potty corner. Then put a litter box in that corner. (clay litter or sand, not fancy litter with things in it the rabbit might decide to eat like chlorophyll crystals.) After your rabbit is used to using the litter box in the cage you can put your cage outside and leave the litterbox inside where the cage was and the rabbit will use it. I personally would not want a rabbit running loose in my home all the time. I would keep the cage in there to lock him up when I was not there for his own safety. Rabbits are very curious and will chew on things like wires if left unattended. I have heard of several rabbits that have electrocuted themselves.
All we did was put a kitty litter try in his hutch and he learnt himself.