How does someone just decide to be a farmer are there classes or do you have to grow up on a farm? how do you acquire the land etc?
Usually it's a family thing.
You don't need land really. Just put on overalls, tuck your thumbs in your armpits and walk around while saying, "sure could use some rain"
Boom, you're a farmer.
Depends on what type of farmer you are (plant, livestock, other), but basically farmers simply grow stuff... so have all the resources to grow stuff and suddenly you're a farmer. (Maybe not legally, as legally different areas you sometimes have to prove it in different ways for tax breaks and other type things).
I also want to add...
Have all the resources and grow stuff is how one can become a farmer, BUT to become a GOOD farmer is a different story, that takes knowledge, effect, hard work and some love.
Grow something and sell it.
If you aren't born into it, it's almost impossible these days, unless you have a lot of capital. The land is generally more expensive than the profit you will make from it as a "startup". (It CAN be done, it's just really tough)
He plants a seed and calls it a farm.
It ain't simple. I've been trying for twenty years. Got pretty good at being a gardener though.