The following procedure will help you create DRS host groups:

1. From the vCenter's inventory home, navigate to the Hosts and Clusters view. Select a cluster, and navigate to Configure | VM/Host Groups.

2. Click on Add..., as depicted in the following screenshot:

3. Provide a name for the group. Select if the group is a VM or host group from the drop-down menu.
4. Add member VMs or hosts to the group and click OK, as depicted here:

5. On completion, you will see the groups created on the landing page of VM/Host Groups.