Using A User Selected Parameter

Ok..............so I'm totally new to this whole SQL thing and I need some help..........please!
I have a table rf_log with the following fields:
PACKSLIP varchar(20)
BINLABEL varchar(8)
EXTENDED varchar(50)
TERMID smallint
USERID varchar(8)
ACTION varchar(8)
QUANTITY int
Q_SCALER smallint
REFERENCE2 varchar(30)
REFERENCE3 varchar(30)
DATE_TIME varchar(23)
DATE_CREAT timestamp(8)
LOCATION varchar(20)
TOTLABEL varchar(20)
CLIENTNAME varchar(15)
PO_NUM varchar(25)
SERIAL varchar(25)
LICENSE_PLATE varchar(22)

What I need to do is to get a list of packslips where the packslip number will BEGIN with the user selected parameter.
For example if the user input is 'ORD000888' then I could possibly get a return of:
Ord000888-0
Ord000888-1
Ord000888-2...............and so on.
I have tried this but unsuccesfully:
SELECT PACKSLIP,BINLABEL,EXTENDED,TERMID,USERID,QUANTITY,Q_SCALER,TOTLABEL,REFERENCE2,REFERENCE3,DATE_TIME, DATE_CREAT,CLIENTNAME,PO_NUM,SERIAL,LOCATION,LICENSE_PLATE
FROM rf_log
WHERE PACKSLIP LIKE ?C

I have also tried:
DECLARE @Pickslip varchar(30)
SET @Pickslip = ?C
SELECT PACKSLIP
FROM rf_log
WHERE PACKSLIP LIKE @Pickslip

None of these worked. Any help would be greatly appreciated.