if he is a muslim, just go to shariat court in doha. When you are coming to qatar, bring with you a "Certificate of singleness", meaning that you are currently not married. He doesn't need such Certificate, as he can have up to 4 wives anyway..:)
it is easy..Go to the court, they will give you a date and time for registering your marriage, then bring 2 witnesses.. 40 minutes- and you are married couple..:)

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"What lies behind us and what lies before us are small compared to what lies within us."
Oliver Wendell Holmes