I am working on LOBS(large objects)and have problem of reading BFILE Stored on my system-

created a table-
1.CREATE TABLE PROPOSAL
(PROPOSAL_ID NUMBER(10) CONSTRAINT PROPOSAL_PK1 PRIMARY KEY,
RECIPIENT_NAME VARCHAR2(25),
PROPOSAL_NAME VARCHAR2(25),
SHORT_DESCRIPTION VARCHAR2(1000),
PROPOSAL_TEXT CLOB,
BUDGET BLOB,
COVER_LETTER BFILE)

2.created a directory as under-
CREATE DIRECTORY PROPOSAL_DIR AS 'D:\PROPOSAL\LETTERS';

3.inserted data into the table-
INSERT INTO PROPOSAL VALUES(
1,'BRAD OHMONT','REBUILD FENCE',NULL,
EMPTY_CLOB(),EMPTY_BLOB(),
BFILENAME('PROPOSAL_DIR','P1.DOC'))

4. Create or replace procedure displaybfile
Is
Lob_loc bfile;
amount integer := 1024;
Position integer := 1;
Buffer raw(1024);
Begin
Select cover_letter into lob_loc from proposal where
proposal_id=1;
Dbms_lob.open(lob_loc,dbms_lob.lob_readonly);
loop
Dbms_lob.read(lob_loc,amount,position,buffer);
dbms_output.put_line(utl_raw.cast_to_varchar2(buffer));
position := position + amount;
end loop;
Dbms_lob.close(lob_loc);
exception
when no_data_found then
dbms_output.put_line('end of data');
End;

5.when I execute this procedure there is error-
ERROR at line 1:
ORA-22285: non-existent directory or file for FILEOPEN operation
ORA-06512: at "SYS.DBMS_LOB", line 605
ORA-06512: at "SYSTEM.DISPLAYBFILE", line 9

QUESTION - I want to open my p2.doc which is text document lying @ "d:\p2.doc" on my system.how to put p2.doc into proposal_dir which is logical directory created as 'D:\PROPOSAL\LETTERS'??
HOW TO MAP PHYSICAL DIRECTORY CONTAINING "P2.DOC" WITH LOGICAL DIECTORY 'D:\PROPOSAL\LETTERS' WHICH I CREATED BY RUNNING-
CREATE DIRECTORY PROPOSAL_DIR AS 'D:\PROPOSAL\LETTERS'
please suggest.
Thanks