Believe it or not horses are very delicate creatures. They can die easily since they can NOT throw up. So anything that goes down that is not good for them will kill them. They are one of the only animals that will eat themselves to death. They also have those delicate legs where injuries can occur.
Not to scare you but read lots of books. Do your research. Take riding and horsemanship lessons. Then maybe consider leasing/renting a horse first before you buy. We don't want you wasting your money or doing harm to a horse.
Find people who you can visit and who can show and teach you about horses. They love to talk about their animals.