YouTube! 
There are also some videos here.
https://shopedss.com/equicast-2-casting-material-for-treating-horse-foot-problems-2-x-4yd/
I use 2" scotchcast
https://a.co/d/1lgumah
You’ll also need adhere, the gun, the tips, and that plastic wrap on a stick stuff. I usually buy from Anvil, their prices are the best. I get 8-10 feet out of each tube of adhere. You’ll need a tip per foot.
If she’s especially tender or thin soled, you can even slap pads under the casts. I’ve used leather pads with a leather based packing with good effect.
It’s really very straightforward! There is a learning curve and it took me a few times to feel competent but stakes are low if they lose a cast (vs walking out of a $$ glue on shoe somewhere in the field.)
I started with the fronts, then started doing her all around after the farrier was just blown away at the amount of heel she grew in front with one cycle, and added the pads/packing late summer when the ground got hard. It’s easy to go back & forth between casting and not.
They are slippery on winter terrain. Not so much loose snow (although they collect snow & snowball like crazy) but if it’s at all slick, they will be SLICK. So maybe something for once you’re past snowy season. We’re almost there!
But two thumbs up highly recommend and that ability to protect them while also making regular very minor adjustments is great.