You have to appear in MOH exam conducted by the National Health Authority (Office opposite to Hamad General Hospital Emergency). They conduct this exam twice a year. Next exam would probably be by the end of this year. This exam would entitle you to work in a private hospital or to establish your own clinic.The eligibility for the exam is to have a specialization or Post Graduate Diploma in any Medical Field after MBBS. If you are fresh graduate... then you can apply for the Residentship in Hamad Medical Corporation. Their next exam would be conducted soon. You can get the application papers from the Hamad Education Centre located inside Hamad General Hospital ... beside the OPD.
If you have done specialization and want to join Hamad Medical Corporation, then you can also go to your related department in Hamad Hospital and can offer your services to them by personally meeting someone responsible there....like the Chairman of the Deptt. If your luck favors you..you would be offered with a Three Months Summer LOCUM.After that its again your luck and performance...they may give you a contract.