Hello,

First create the new filegroup

USE master

GO

ALTER DATABASE Test1

ADD FILEGROUP Test1FG1

GO

ALTER DATABASE Test1

ADD FILE

( NAME = test1dat3,

FILENAME = 'k:\SQL\database.NDF',

SIZE = 200GB,

FILEGROWTH = 10GB)

TO FILEGROUP Test1FG1

Then rebuild the clustered index into the new filegroup created

CREATE CLUSTERED INDEX CIX_YourTable

ON dbo.YourTable(YourClusteringKeyFields)

WITH DROP_EXISTING

ON [Test1FG1]

And that's it. I hope this can clear things up.