Newbie help how to store and backup iTunes library

It must be an age thing--pushing sixty and I can't make heads or tails out of the advice on the Computer Audiophile site. I just want to move my iTunes library from the internal hard drive on my Sony Vaio laptop to an external hard drive, and simultaneously back it up on another hard drive. I would like for the external drives each to have at least 3 TB of storage. I would like for them to be linked so that the backup drive regularly and automatically updates. And I'd like the drives to work with a Mac Mini, which I'm thinking about buying to use as a music server. If you can recommend specific hardware, I'd appreciate it. Or if I'm going about the storage-and-backup the wrong way, please set me straight. Thanks.