Create Cluster in vCenter Server 5.1

1. Create on Hosts and Clusters view and expand the Datacenter and Right Click select New Cluster
2. It will display New Cluster Wizard
3. We will enable HA/DRS simultaneously
4. It will create new Cluster with the name specified
5. Once the Cluster is created we can move the Host to the Cluster
6. Right Click on the Host and Select Move To
7. Navigate through to Cluster and Click OK
8. It will ask to confirm whether Resource Pool needs to be created or Add in Default Resource Pool
9. In the Recent Tasks it will display the task
10. It will display Completed once done
11. Similarly you can add all the Hosts Required

http://vcommunique.blogspot.in/2012/12/create-cluster-in-vcenter-server-51.html