Redirect output in a file in Oracle PL SQL

There are different ways:
a) Before you execute the package you can enable SPOOL.
or
b) Create a temporary package and insert the log messages into that so that data can be viewed later on the temporary table.
or
c) Use DBMS_FILE package procedure to open and write data into files.

To Create file using PL/SQL this may be useful

http://nimishgarg.blogspot.in/2011/09/create-csv-file-using-plsql.html