Hello,
There are a lot resources available in prior and this year's Insight presentations (https://www.brainshark.com/go/netapp-sell/insight-library.html?cf=8344), on the Support site (Support.netapp.com), and through NetAppU classes at http://learningcenter.netapp.com/ (through courses like ONTAP Cluster Administration, ONTAP NFS Administration, ONTAP SAN Administration, ONTAP SMB (CIFS) Adminstration, Performance Analysis).
A good place to start is Technical Report 4211 Storage Performance Primer Clustered Data ONTAP 8.3 (http://www.netapp.com/us/media/tr-4211.pdf).
Good luck in your learning.
Curtis Burchett
Senior Manager, Worldwide Technical Delivery
Post-Sales Americas Delivery Team
NetApp University