Before you start, there are some facts to know. Kits chill very quickly and easily, so must be kept warm and dry. Kits have very little energy reserves and need to cat within an hour or so of birth, especially if they become chilled. The average temperature in the nest of healthy kits is considerably higher than human body temperature, so simply getting them 'body warmed' is not good enough for full recovery. To read more, go here: Bottle Feeding A Baby Rabbit
Other things you can do.
1. Get the kit warm - the easiest way I have to do this is to plop them into another litter as fast as possible. The kit will warm up quickly and naturally without getting over heated. If putting in with an older litter make sure the kit doesn't get buried in the bottom and suffocates. You may have to warm towels in a drier, use a hair dryer (set on low), use a hot water bottle or something else.
2. Easiest way to raise a foster is to give them to another doe. Most does won't have a problem fostering, but some will. You only know if you stay and watch their reaction, but for most rabbits with newborns its just a matter of plopping the kits into the nest and just leaving.
3.If another doe is not an option you'll need to look into bottle feeding and realize its not an easy road. Some folks have the knack for it and others don't. You won't know if you are one who does unless you give it a whirl.
Some folks have put milk on a cloth and let the kits suck the cloth. This prevents them from breathing in milk and essentially drowning. Different options the older the kits get. :)
The easiest is always to find a doe who will raise them for you. :)