Q: How can I share my library with all my devices

In the article Share your iTunes library over your home network - Apple Support its pretty simple from what I have read, you just have to make sure that you have the sharing options enabled in iTunes on your computer.

You just have to make sure that you are signed into the same Apple ID on all of your devices and turn on home sharing on all of them as well, and make sure that you are connected to the same network when trying to share the library.