How to start a cow farm
If you mean "how can I start a cattle ranch", I can offer an answer based on my family's experience in Northern California. My mom and dad retired to ten acres of land in the late seventies. My dad was NOT a farmer when he retired; he was a general manager of an industrial laundry, which is as far away from "cow farming" as one could get.
But that didn't stop them from wanting to raise cattle for beef. My dad's approach was very simple; he talked to his ranching neighbors about where to buy beef calves, what kind of food was the best for good flavored beef, how often they needed to be fed (this was in addition to letting them free-graze), how to give them access to water (put a trough next to their barn and run a water line to it), and make sure the land had adequate fencing.
The hardest part? Not getting attached to the cows. Because once they get big enough to slaughter, you have to make the decision to actually do that. Cows are like dogs. They will follow you around, want to have their heads scratched, and they will look you in the eye with a great deal of intelligence and humor. If after a couple of years of having a thousand pound cow/dog following you around while you bring them hay and grain and muck the barn (oh yeah, did I mention they poop really big piles of stinky, hay filled poop EVERYWHERE?), you still have the stomach to send them off to slaughter, then actually EAT THEM, all you have to do is call a slaughterhouse. They will make you a deal to pick them up and they will slaughter them and carve them up into cuts of beef and will package them for your consumption.
One more important piece of advice though: do NOT tell your children they are eating Bessie for dinner. They will never, ever eat beef at your house again.