Back up libraries
In order to avoid the loss or damage of your computer, you can back up the library anytime and anywhere and it's quite simple. You only need to copy/paste the library.
Step1: Open the saving path of the library
Open the saving path of the library, right-click the library and select Copy.
Step2: Copy and paste the library to other devices(ex: external hard drives)
Open the folder where you want to store the backup, paste the library to here and the backup is complete.
If you want to back up easily, you can considerate to use more professional tool to achieve this purpose. This professional software can usually do the functions of backup schedule and incremental backup.
You can use Time Machine, the built-in backup feature of your Mac, to automatically back up all of your files.
Incremental backups can be easily implemented using professional software like Arconis. You can schedule specific hard drives and folders to back up them according to your needs.