Sometimes it goes easy, sometimes it takes some work and patience.
Place the cages next to each other, and let the new bunny out into thefirst rabbit's territory. That way their scents will merge, and theycan investigate each other through the cage safely. Don't let them outin that space together at first though, just let them get used to eachother's scent.
When it comes time to do some bonding, do it in a neutral space, suchas a bathroom. It's handly to have a spray bottle on hand too.Sometimes it's love at first sight, and if so, more the better. If not,it can still be done. I put food and water down too,which can be astress reliever.
Supervise them closely. As soon as you see signs of aggressivebehavior, such as ears flat against the head, slap your hands loud todistract. If they do fight, a good spray will usually stop it, or atowel to toss on them so you don't get scratched or bit. Expect somefur to fly though.
Do this for about 20minutes at a time, twice a day. Before,you may want to put them in the same carrier and take them on a short,ten minute car drive, then the bathroom time. What I did was sit therevery quietly and just watched. If they ignore each other, great. That'swhat you want. If they start to groom each other, it's a done deal.
It took me about two weeks to get my first rabbit to accept the newrabbit. I actually have three, but the first two bonded instantly and Ihad literallyno fights. A doe/buck mix is the best. I nowhave two bucks anda doe, the third rabbit being a buck. Itwas my doe who wasn't accepting him, she was very aggressive towardshim. I just about gave up hope, but now all three of my rabbits are inthe same cage and all are bonded. It can be done! Just have patience,it'll happen.