welcome to our world
you should be able to lease a horse for the day that is an experienced fox hunter. This will cost $100-$150 for a day. After that, you might be able to lease a hunt horse for a season, or more, depending on what the owner wants to do.
go to www.mfha.com/memb. and find the hunts in your area and write to the secretary. they often know of someone in the hunt that will lease you a horse. also, potentially a member that is a trainer/instructor that will give you some lessons related to skills for the hunt field.
There is a wealth of info and useful links on the home page for the MFHA. and look into the archive for this forum; a great deal of hunting wisdom has been posted, including other threads similar to this one
As to what you need to know, you need to be comfortable riding over all types of terrain, fit enough to ride for at least 2 hrs (or longer; you will need to find out about the hunt you will attend), and comfortable at a gallop (although, you may be able to hunt in a “hilltopper” group that mostly trots or goes at a very controlled canter). Just in case, you should learn emergency stopping techniques.
Most hunts allow guests to “cap in” ie come just for the day and pay a cap fee, usually ~$50. Again, this can be initiated with the secretary, although you may need a member to be your host for the day. Most hunts want new members, and having them first as guests is a a good start.
If you have your own truck/trailer and horse then the main cost is the cap fees. Of course once you are addicted to the sport like the rest of us, and become a member of a hunt, there are membership dues, typically ~$1000/yr (although I am sure many hunts are more). members are also expected to help with many tasks, such as walking hounds, and riding and maintaining the territories, and prepping food for “teas” (lunch or breakfast after a hunt).