How to use initcap function in sql server?

CREATE FUNCTION [dbo].[InitCap] ( @InputString varchar(4000) )  
RETURNS VARCHAR(4000) 
AS 
BEGIN
  DECLARE @Index INT 
  DECLARE @Char CHAR(1) 
  DECLARE @PrevChar CHAR(1)
  DECLARE @OutputString   VARCHAR(255)
  SET @OutputString = LOWER(@InputString) 
  SET @Index = 1
  WHILE @Index <= LEN(@InputString)
  BEGIN
     SET @Char     = SUBSTRING(@InputString, @Index, 1)
     SET @PrevChar = CASE WHEN @Index = 1 THEN ' '
                          ELSE SUBSTRING(@InputString, @Index - 1, 1)
                     END
     IF @PrevChar IN (' ', ';', ':', '!', '?', ',', '.', '_', '-', '/', '&', '''', '(')
     BEGIN
         IF @PrevChar != '''' OR UPPER(@Char) != 'S'
             SET @OutputString = STUFF(@OutputString, @Index, 1, UPPER(@Char))
     END      
     SET @Index = @Index + 1 
 END
 RETURN @OutputString
END
GO