how does one begin to train for events such as these?

[Alan H]

are there training "facilities" anywhere or do you folks just have at it in a large open field and homemade devices?

That's exactly what we do. I'm lucky in that I work at Stanford University, which has a large Intramurals athletic field complex not far from my job site. There's some bare ground, oak trees for shade, and lots of grass. We throw from the grass onto to the bare ground, mostly, so as to not mess up the playing fields. I think the groundskeepers appreciate that.

Read through that thread, up there and get started. If you want to do some weight training (highly recommended, if you want to get semi-serious about it) I have a thread on this board which has some suggestions.