After recieving the job offer you have to go to the staff clinic and register for your medical test. they will give you appointment after that you will have blood test and x-ray test in HGH.

CID - you have to go to CID office and get an application form. then attach the qualification certificate which is attested from native and foriegn affairs office in doha, police clearance certificate along with this and submit to CID office.

they will give you a slip return that slip to HR.

hope this will be helpful...