If the system is already installed, connect the disk to the system and perform a reconfiguration boot. 

SPARC: Adding a System Disk or a Secondary Disk (Task Map)

Repartition the disk with the format utility, if necessary.

SPARC: How to Create Disk Slices and Label a Disk

Create disk volumes, and if needed, create soft partitions with Solaris Volume Manager. 

Chapter 2, Storage Management Concepts, in Solaris Volume Manager Administration Guide

Create UFS file systems for the new disk with the newfs command.

SPARC: How to Create a UFS File System

Or, create a QFS file system. 

http://docs.sun.com/db/coll/20445.2