To begin, place your .dmp file in your admin\XE\dpdump\ folder. I am running my server locally on my laptop, so this location is
This location may be different depending on where you installed oracle. I prefer to put my dump files in the dpdump folder so that I don't have to specify a directory when doing the import.
Next you should open up your command line utility and type the following command
impdp username/password dumpfile=FILENAME.DMP
The data pump import utility will begin running and outputting it's progress to the screen. It will generate your tables, triggers, binds, and fill the data in. Basically it will make an exact replication of the database it was exported from. After this is complete check your errors. If there were none, you're good to go!
Hopefully this tutorial helps you get through this task without having to scour the internet. Take care, and good luck with Oracle!