@splitloops - if you can't understand the first post, then just do some googling to find examples from others. For instance this post is quite good:
I personally don't agree with its "recommendation" to use a custom column, I think for most users requirements (like having collections by author) the simplicity of an automatic collection is the way to go. That is what I use. But if you want more flexibility then a custom column will give you that.
Then all you have to do is plug in your device, send books to your Kindle, then click on the Kindle Collections icon to get it to regenerate your collections for you - eject the device, restart it and job done.
Alternatively you can use the Reading List plugin to allow you to queue up books for when the Kindle is next connected, and it can be configured to automatically call this plugin and regenerate the collections, saving you remembering to click.
It doesn't get any simpler than that - the only hard part is the initial configuration.