Newbie question: How to CREATE FUNCTION

Hi,

I am new to PostgreSQL. So, please forgive my ignorane.

Can anyone tell me how to create a FUNCTION in PostgreSQL that performs the
same duty as the following MsSQL stored procedure?

*********************************************************
Create PROCEDURE AddEmployee
@Name NVARCHAR(255)
,@Title NVARCHAR(255)
,@strErr VARCHAR(255) OUTPUT

AS
BEGIN

/* ~~~ Add the employee into the Employees table ~~~ */
INSERT INTO Employees
( name
,title
)
VALUES
( @Name
,@Title
)

/* ~~~ Error checking ~~~ */
IF( @@rowcount = 0 )
BEGIN
SELECT @strErr = 'Errors adding the new employee.\n'
RETURN -1
END
/ * ~~

/* ~~~ Return the auto id through the OUTPUT parameter ~~~ */
SELECT @strErr = CONVERT(VARCHAR(255), @@IDENTITY)
RETURN 0

END
*********************************************************

Can you also tell me how to add a new language (if necessary) like pgsql
into PostgreSQL? Pointers to learning pgsql will also be appreciated.

Thanks a lot in advance!

Steven