How to export and import dat from oracle server user expdp and impdp

create directory mydirectory as 'd:\data\dumpdir';
select * from dba_directories;
grant read,write on directory mydirectory to myusername;
expdp myusername/newuser@xe  DIRECTORY=mydirectory schemas=myusername dumpfile=myusername.dmp
///////////////////////////////
DEFINE usr_name = myusername
DEFINE usr_pwd  = newuser

--DROP USER &&usr_name CASCADE;

CREATE USER &&usr_name IDENTIFIED BY &&usr_pwd
  DEFAULT TABLESPACE mig_data
  TEMPORARY TABLESPACE mig_temp
  QUOTA UNLIMITED ON mig_data
  QUOTA UNLIMITED ON mig_index
  QUOTA UNLIMITED ON mig_lob;

GRANT ALTER SESSION,
      CREATE CLUSTER,
      CREATE DATABASE LINK,
      CREATE SEQUENCE,
      CREATE SESSION,
      CREATE SYNONYM,
      CREATE TABLE,
      CREATE TYPE,
      CREATE VIEW,
      CREATE PROCEDURE,
      CREATE TRIGGER,
      CREATE MATERIALIZED VIEW,
      QUERY REWRITE
  TO &&usr_name;
//////////////////////////////
impdp myusername/newuser@xe schemas=myusername directory=mydirectory dumpfile=myusername.dmp logfile=myusername.log