Stored Procedure Newbie

I am trying to write a stored procedure to do the following below:

The printed check file has a name that looks like this: A111111B222222222C3333333333D50E50.PDF.*
In the example name above, 111111 is the check number, 2222222222 is the routing number and 3333333333 is the account number.

The letters define the piece of data that follows.* *
·******** A = Check number
·******** B = Routing number
·******** C = Account number

Steps:
a. stored procedure to pull the check number, routing number and account number from tblCheckRegister.
b. Join them together in proper format.
b. Once it has done that, do a wildcard search on a table called tblSIValidate column SIBarCode.
c. The return value should be the entire SIBarCode column.* Append the .PDF to it and look in the same image directory as the cancelled check.




I am used to VB.net and vbscripting and the syntax there. I am sure there are things below in the stored procedure that are not correct.
Any help is appreciated.


---------------------------------------------------------------
STORED PROCEDURE
---------------------------------------------------------------


/*
Name: usp_GetCheckImage
Description: Gets Printed Check
Author: Mike
Modification Log: Change

Description Date Changed By
Created procedure 12/15/2007 Mike Belcher
*/

CREATE PROCEDURE dbo.rx_bhd_GetCheckImage
@maillogid int,
PrintedCheckFile OUTPUT
AS

SET NOCOUNT ON

/* Get Check#, Routing#, and Account# */
SELECT CheckNo, CPRoutingNumber, CPAccountID
FROM tblCheckRegister
WHERE maillogid = @maillogid


/* Combine Check#, Routing#, and Account# into proper format */
declare @PrintedCheck char(255)

@PrintedCheck = "a"

@PrintedCheck = "A"
@PrintedCheck = @PrintedCheck & CheckNo

@PrintedCheck = @PrintedCheck & "B"
@PrintedCheck = @PrintedCheck & CPRoutingNumber

@PrintedCheck = @PrintedCheck & "C"
@PrintedCheck = @PrintedCheck & PAccountID



/*
if @PrintedCheck = null
Give dummy value
*/



/* Search tblSIValidate column SIBarCode combined PrintedCheck# Example: "A111111B222222222C3333333333" */
SELECT SIBarCode
FROM tblSIValidate
WHERE SIBarCode LIKE @PrintedCheck



/* Need to return the @PrintedCheckFile */
SET @PrintedCheckFile = SIBarCode & ".pdf"


GO