Hi!
There are many ways to set up ZFS pools, depending on the use case.
As you are new, I would recommend not using more than half your capacity till you are comfortable, and making sure you have a copy of the data on the other half.
Then if it all goes wrong, you are not scuppered.
Later on, you might use that storage as an actul backup, once you have the system running fine, and you have practiced recovering from faulted drives and stuff.