Hi Negeswara,
I recomend the next redbook
WebSphere Application Server V6 Scalability and Performance Handbook
www.redbooks.ibm.com/abstracts/SG246392.... even is for version 6 the steps to create a cluster in v7 are the same.
The sample topology is quite advanced, but real for production environments. If you are starting I suggest a subset of the sample topology:
Two nodes (physical/virtual). One of then (A) with Deployment Manager (DMGR) and 1 Node (Federate) and the other one (B) with HTTP Server and other Node (Federate).
Then create a cluster of two menbers between node A and B.
To do that follow Chapter 8.5 Installing WebSphere and configuring clusters. Don't do section 8.5.6, with section 8.5.5 you will have one cluster implemented.
For HTTP server implementation follow Chapter 8.6 Installing and configuring IBM HTTP Server 6.0.
Hope this helps. Tell us any doubt about the implementation process.
regards