Mahbub Bhai Assalamu-Alaikum.

As I know you required, Letter from your sponsor, Bank Statement for last three months showing your salary transfer, Marriage Certificate(Kabin Nama) in Arabic/english attested by Qatar embassy in Bangladesh(Gulshan, Dhaka) and you have to face an short interview by Immigration officer after submitting all documents to them. However, you can ask your company's PRO (Mandoop)to know more in details about it.

Dhonnobad