Inside Qatar PCC you have to apply personally by filling out this form:
http://www.moi.gov.qa/site/arabic/departments/CriminalDept/resources/2010/06/13_17245.pdf
then print it out and go to "search and follow up department" at Salwa road and apply there. Don't forget to bring 2 photos and a copy of your passport and Qatari ID.
Outside Qatar, I think you have to contact your nearest Qatari embassy or consular mission.
It will take a maximum of 7 days and it is bi-lingual (Eng-Ara) so no need for a translation.
Best wishes