Were can I find laws about this and owning horses in my area? I can't seem to find anything
Not sure about FL, but in NY there are two primary places for finding these laws. Many are spelled out in the traffic laws. Others are spelled out in the "market" laws (state laws that govern agricultural/farming). I would think that most states have _something_ about horses in traffic/motor vehicle code.
Owning horses is a different thing. While there may be some state level rules, the bulk of the matter is likely to be a local issue. Your county, city, town, etc. probably has various laws or zoning restrictions on owning/keeping livestock.
I have found that most state level info can be found online. Below that level online access is very hit or miss.
FWIW, in New York it is very clear that horses are supposed to travel with the flow of traffic (right side of road). They are also required to stay to the right and ride to the shoulder where possible. So while the cars are supposed to yield to horses, there is also responsibility on the rider to keep out of way of traffic (which should be common sense).