There are two necessary manuals you should read and understand for the use of ControlLogix Redundancy.
The first is the ControlLogix Redundancy User Manual, which covers the basic principles of ControlLogix Redundancy. There is also a newer Enhanced Redundancy User Manual that includes the newest modules and functionality.
The second is the Release Notes publication for the specific version of Redundancy you are going to use. The modern 1756-RM redundancy module requires different network and controller modules than the older 1756-SRM module, and the firmware and hardware versions described in the Release Notes must be followed exactly.
All RA Publications can be downloaded from the Rockwell Automation Literature Library. Use the Search function with the Keyword "ControlLogix Redundancy" to find the publications related to Redundancy.