I have a dump file which includes two tables. Now I need to import this dump file. I was instructed to create two tablespaces beforehands.Now how do I import this dump file
You CAN import a dump file from PL/SQL developer. Tools -> Import Tables... -> (at the botton of the popup screen) select the file and click in "Import".
You cannot import a dump file from PL/SQL developer. Instead, you have to do it from the command line. Furthermore, you need access to the file system of the database server since you have to put the dump file in a directory directly accessible by Oracle.
The tool to import the dump file is called impdp (in earlier version, it was imp).
My experience is that you need information how the dump file was created so you can use the correct import mode:
You'll find more information about impdp on this PSOUG web page.