Why do it? It's a terrific training and management tool.
How do to it? Getting a dog used to a crate involves treats, praise, toys, kong toys and you can feed them in their crate to so they associate their crate with all positive good things. Doing it in short intervals is key.
Don't do. Don't use the crate as punishment. So if you yell at your dog then put your dog in the crate, your dog will associate the crate bad things and will start to not want to go in the crate. Then all your work will be undone.
If you have any questions, feel free to call or email me for more information.