You will need a second cage or pen or crate for the new rabbit. Even if the new rabbit is already spayed, you still have to let her settle in for a week or two before you can start bonding or pre-bonding, so she will have to be kept separated from your male. If she isn’t already spayed, then that will have to be done if she is old enough, then there will be a few weeks of recuperation and waiting for her hormones to dissipate until you can begin bonding. Bonding can be quick and easy, or it can take weeks, even months, and in some rare cases, it never works, and the rabbits will have to be kept separately forever, unless you rehome one.
The article on bonding in the BUNNY INFO section is here – https://binkybunny.com/BUNNYINFO/tabid/53/CategoryID/9/PID/940/Default.aspx,
Another good article is found here – https://rabbit.org/faq-bonding-multiple-rabbits/
I have had good luck using an x-pen for bonding. My husband and I get in the pen along with the bunnies. We are there to stop any fighting (some scuffling can be normal) or to stop excessive humping. We start out with a few minutes the first day, the increase the time a little each day. I have never done pre-bonding, but many people do. That’s where you swap out blankets, toys, cages, etc., anything with a rabbit’s scent to get them used to each other.