There are several places where you can learn more about Essbase.
Use the following links to learn more about Essbase in Oracle Enterprise Performance Management System.
For all Essbase and EPM documentation, use the Performance Management Documentation page:
http://www.oracle.com/technetwork/middleware/performance-management/documentation/index.html
This page also contains links to EPM System Supported Platform Matrices, My Oracle Support, and other information resources.
Drill down to view specific documents for a release.
For information about meeting system requirements and understanding release compatibility, use Oracle Enterprise Performance Management System Certification Matrix:
http://www.oracle.com/technetwork/middleware/ias/downloads/fusion-certification-100350.html
When Essbase is installed as part of Oracle BI Enterprise Edition, refer to System Requirements and Supported Platforms for Oracle Business Intelligence Suite Enterprise Edition for information about system requirements and release compatibility.